Evaluation of the manual hexadimethrine bromide (Polybrene) technique in the investigation of autoimmune hemolytic anemia I. OWEN AND J. Hows The use of the direct manual hexadimethrine bromide (Polybrene) test (DPT) in the investigation of patients for autoimmune hemolytic anemia (AIHA) was evaluated. Seventy-nine blood samples from 68 patients were tested. A direct antiglobulin test (DAT) using monospecific reagents and the DPT were performed, and a concentrated ether eluate was tested. The DAT was positive in 62 (78%) of 79 patients and negative in 17 (22%). There is a good correlation among DAT, eluate, and DPT in demonstrating the presence of immunoglobulin on the red cell surface. In contrast, the DPT does not detect C3d and is often negative in cases of AIHA in which C3d alone is demonstrated by the DAT. In DAT-negative cases, DPT results correlated with reactive eluates. However, in four cases of steroid-responsive, DAT-negative hemol ic anemia, the DPT supported the diagnosis of AIHA when the eluate did not it is not recommended as a replacement for either eluate testing or the DAT. TRANS- FUSION 1990;30:814-818. react. r he DPT is a useful additional screening test for the investigation of AIHA, but THE INDIRECT HEXADIMETHRINE bromide (Polybrene) test (IPT), first described by Lalezari‘ as an automated method and then by Lalezari and Jiang2 as a manual technique, has been widely used in the detection of al- loantibodies. In that context, it has been found in many instances to be more sensitive than other techniques. However, some antibodies that are detectable by stan- dard techniques are not identified by the IPT.3-5 The present study is an evaluation of the manual direct Po- lybrene test (DPT) previously described by Petz and BranchG and Lalezari7 for use in the investigation of patients with suspected autoimmune hemolytic anemia (AIHA). Other workers in the field have evaluated the use of the DPT in the investigation of AIHA8s9 and have found it to be valuable in regard to cases of direct antiglobulin test (DAT)-negative AIHA. In these investigators’ hands, the DPT seemed to be as sensitive as much more so- phisticated tests, such as the red cell (RBC) enzyme- linked antiglobulin test, and functional assays, such as the monocyte/macrophage phagocytosis How- ever, the investigations were carried out in only a small number of patients. We have now evaluated the DPT in a larger number (121) of patients undergoing investiga- tions for AIHA and have compared the results in DAT- positive and -negative cases with those obtained by test- ing concentrated ether eluates. ~ From the Department of Haematology, Royal Postgraduate Medical Received for publication August 16, 1989; revision received March School, Hammersmith Hospital, London, UK. 12, 1990, and accepted April 3, 1990. Materials and Methods Blood samples We collected whole blood into either ACD or EDTA or defibrinated it.’” Unless otherwise stated, we washed the RBCs four times in phosphate-buffered saline (PBS), pH 6.9. If cold agglutinins were suspected, washing was carried out at 37°C. DAT Standard centrifugation techniques were used for the DAT. We tested the washed cells with monospecific anti-IgG, -C3d, -IgA, -IgM, and a saline control. Eluates RBC eluates were made using Issitt’s modification” of Rub- in’s ether elution technique.12 We added saline to washed RBCs in a ratio of saline to packed cells varying from 1:l to 1:4, according to the amount of immunoglobulin found on the RBC surface in the DAT. We added a volume of ether equal to that of the cells and saline, shook the tubes for 1 minute, and incubated them for 30 minutes at 37°C with intermittent shak- ing. The tubes were centrifuged, and the eluate was removed and incubated at 37°C until all the ether had been evaporated off. We then tested the eluates against a pool of three group 0 screening cells by a two-stage papain technique and by the indirect antiglobulin test (IAT). Two-stage papain technique. We diluted the eluate in PBS to 1:l through 1:32. We then incubated the dilutions for 1 hour with 2 to 4 percent suspension of papainized pooled group 0 cells and read them microscopically for agglutination. IAT. We incubated the eluate for 1 hour with pooled group 0 cells. We washed the RBCs four times and tested them with monospecific anti-IgG, -C3d, -IgM, -IgA, and a saline control. Anti-IgG and -C3d were supplied by the Blood Group Ref- erence Laboratory (Oxford, UK); anti-IgA and -1gM by the Scottish Antibody Production Unit (Glasgow); and papain by the North London Blood Transfusion Center. 814
Transcript
Evaluation of the manual hexadimethrine bromide (Polybrene) technique in the investigation of autoimmune hemolytic anemia
I. OWEN AND J. Hows
The use of the direct manual hexadimethrine bromide (Polybrene) test (DPT) in the investigation of patients for autoimmune hemolytic anemia (AIHA) was evaluated. Seventy-nine blood samples from 68 patients were tested. A direct antiglobulin test (DAT) using monospecific reagents and the DPT were performed, and a concentrated ether eluate was tested. The DAT was positive in 62 (78%) of 79 patients and negative in 17 (22%). There is a good correlation among DAT, eluate, and DPT in demonstrating the presence of immunoglobulin on the red cell surface. In contrast, the DPT does not detect C3d and is often negative in cases of AIHA in which C3d alone is demonstrated by the DAT. In DAT-negative cases, DPT results correlated with reactive eluates. However, in four cases of steroid-responsive, DAT-negative hemol ic anemia, the DPT supported the diagnosis of AIHA when the eluate did not
it is not recommended as a replacement for either eluate testing or the DAT. TRANS- FUSION 1990;30:814-818.
react. r h e DPT is a useful additional screening test for the investigation of AIHA, but
THE INDIRECT HEXADIMETHRINE bromide (Polybrene) test (IPT), first described by Lalezari‘ as an automated method and then by Lalezari and Jiang2 as a manual technique, has been widely used in the detection of al- loantibodies. In that context, it has been found in many instances to be more sensitive than other techniques. However, some antibodies that are detectable by stan- dard techniques are not identified by the IPT.3-5 The present study is an evaluation of the manual direct Po- lybrene test (DPT) previously described by Petz and BranchG and Lalezari7 for use in the investigation of patients with suspected autoimmune hemolytic anemia (AIHA).
Other workers in the field have evaluated the use of the DPT in the investigation of AIHA8s9 and have found it to be valuable in regard to cases of direct antiglobulin test (DAT)-negative AIHA. In these investigators’ hands, the DPT seemed to be as sensitive as much more so- phisticated tests, such as the red cell (RBC) enzyme- linked antiglobulin test, and functional assays, such as the monocyte/macrophage phagocytosis How- ever, the investigations were carried out in only a small number of patients. We have now evaluated the DPT in a larger number (121) of patients undergoing investiga- tions for AIHA and have compared the results in DAT- positive and -negative cases with those obtained by test- ing concentrated ether eluates.
~
From the Department of Haematology, Royal Postgraduate Medical
Received for publication August 16, 1989; revision received March School, Hammersmith Hospital, London, UK.
12, 1990, and accepted April 3, 1990.
Materials and Methods
Blood samples We collected whole blood into either ACD or EDTA or
defibrinated it.’” Unless otherwise stated, we washed the RBCs four times in phosphate-buffered saline (PBS), pH 6.9. If cold agglutinins were suspected, washing was carried out at 37°C.
DAT Standard centrifugation techniques were used for the DAT.
We tested the washed cells with monospecific anti-IgG, -C3d, -IgA, -IgM, and a saline control.
Eluates RBC eluates were made using Issitt’s modification” of Rub-
in’s ether elution technique.12 We added saline to washed RBCs in a ratio of saline to packed cells varying from 1:l to 1:4, according to the amount of immunoglobulin found on the RBC surface in the DAT. We added a volume of ether equal to that of the cells and saline, shook the tubes for 1 minute, and incubated them for 30 minutes at 37°C with intermittent shak- ing. The tubes were centrifuged, and the eluate was removed and incubated at 37°C until all the ether had been evaporated off. We then tested the eluates against a pool of three group 0 screening cells by a two-stage papain technique and by the indirect antiglobulin test (IAT).
Two-stage papain technique. We diluted the eluate in PBS to 1:l through 1:32. We then incubated the dilutions for 1 hour with 2 to 4 percent suspension of papainized pooled group 0 cells and read them microscopically for agglutination.
IAT. We incubated the eluate for 1 hour with pooled group 0 cells. We washed the RBCs four times and tested them with monospecific anti-IgG, -C3d, -IgM, -IgA, and a saline control.
Anti-IgG and -C3d were supplied by the Blood Group Ref- erence Laboratory (Oxford, UK); anti-IgA and -1gM by the Scottish Antibody Production Unit (Glasgow); and papain by the North London Blood Transfusion Center.
814
TRANSFUSION 1990-VoI. 30. No. 9 POLYBRENE IN AIHA 815
DPT The DPT was based on the method of Petz and BranchYh
which in turn was based on that of Lalezari and Jiang.2 We incubated washed patient RBCs for 1 minute in low ionic me- dium and AB serum. We added Polybrene and centrifuged the test tube. After decanting, we added resuspending solution and immediately read the tests. During the course of these inves- tigations, various modifications, described below, were introduced.
Saline. We used saline as a suspending medium for the RBCs, as a diluent for the Polybrene, and, in the earlier in- vestigations, as a diluent for AB serum. The DPT was per- formed with both unbuffered saline and PBS, pH 6.9. There was no consistent difference between the two, and so for con- venience, we adopted the use of PBS throughout.
AB serum. Initially, 5-percent AB serum in PBS was used for diluting the anti-D in the positive control, as the negative control, and, except where otherwise stated, in all the DPTs. We found that the use of undiluted AB serum, as compared to 5-percent AB serum, tended to enhance the reaction of the positive control. Neat AB serum was also a more satisfactory control when undiluted patient serum was used in the IPT and when, in some instances, undiluted patient serum replaced the AB serum in the DPT. We therefore adopted the use of un- diluted AB serum as the standard technique.
Low ionic medium. The low ionic medium (LIM) was made up according to Lalezari and Jiang.* We evaluated the effect of using LIM at its standard pH (4.5-4.7) and at an adjusted pH of 6.4. From the results of this comparison (Table l ) , we concluded that the adjusted pH of 6.4 is the most satisfactory in the DPT. However, on four occasions, the DPT was en- hanced at pH 4.5. It is therefore important to repeat at pH 4.5 all DPTs that were negative at pH 6.4. The use of 0.6 mL of LIM was more economical than 1 mL, and the change did not affect sensitivity.
Supplementary antiglobulin test. We tested seven of the samples by the supplementary antiglobulin test (SAT), using the method of Lalezari and Jiang2 Four of the seven samples that had been positive on the DPT were either negative or much weaker on the SAT. One sample gave a stronger positive re- action on the SAT and two were positive on the SAT but negative on the DPT. Our current procedure is to test by the SAT all samples that are negative on the DPT.
Resuspension phase. We found that, after the test tubes had been centrifuged and the supernatant removed, we obtained
Table 1. Evaluation of DPT* and lPTt using L/M# solutions of different pH
Enhanced at Enhanced at pH 6.4 pH 4.5 to 4.7 pH-independent
DPT 9 (215 4 (0) 12 I PT 2 (2) 0 (0) Positive control
UPT) 2 (1) 8 (1) Total numbers 13 (5) 12 (1)
0
14 26
Total number tested 51
‘Direct Polybrene test. tlndirect Polybrene test. *Low ionic medium. §Figures in parentheses represent the numbers of tests that were positive only at t h e preferred pH.
increased sensitivity by leaving the tests at room temperature (RT) for 3 to 5 minutes before adding the resuspending solu- tion. If we left the tubes for more than 5 minutes, the sensitivity continued to increase but weak false-positive reactions occurred.
Patients’ RBCs. Usually, we washed patient RBCs four times in PBS. In five of the patients with apparent AIHA and negative DATs, nonreactive eluates, and negative serum screens, we also tried using unwashed cells suspended i n autologous serum or plasma’ or AB serum. We found that the cell samples of three of the five patients were negative on DPT, whether we used washed or unwashed RBCs, or AB or aulologous serum. Both of the two samples that were positive on DPT were more strongly positive when unwashed RBCs were used.
Temperature. If reagents stored at 4°C were used before equilibration at room temperature (RT) had occurred, there was a marked decrease in sensitivity. On the basis of the above assessments, we now use the
following technique for the DPT.
Modified DPT method Reagents. We use Polybrene at a stock solution of 10 per-
cent Polybrene in 0.9 percent sodium chloride, and a working solution of the stock diluted 1 in 250 in PBS. LIM consists of 5 percent dextrose containing 2 g per L of disodium EDTA, with the pH adjusted to 6.4. The resuspending solution is 60 mL of 0.2M trisodium citrate and 40 mL of 5 percent dextrose. The washing solution consists of 50 mL of 0.2M trisodium citrate and 950 mL of 0.9 percent sodium chloride. PBS is 0.9 percent sodium chloride buffered to pH 6.9.
Method. For the positive control, we dilute an IgG anti-D in AB serum, using a dilution that will give a positive result with papainized cells but that is negative on IAT (e.g., 1 in 10,000 is often suitable). We use group 0, D + RBCs. For the negative control, we use AB serum with any group 0 cells.
Test. We wash the RBCs four times in PBS, make a 3- to 5-percent suspension in PBS, and set up tests in 75 x 10-mm tubes (Table 2). To each tube, we add 0.6 mL of LIM, pH 6.4, and leave the tube at RT for 1 minute. We then add 2 drops of working Polybrene to each tube, mix gently, and leave for 15 seconds at RT. We centrifuge the tube at 1000 x g for 15 seconds and then decant the supernatant, taking care to remove i t all. We leave the tubes 3 to 5 minutes at RT, then add 2 drops of resuspending solution, and mix gently.
Within 10 seconds, aggregates dissociate, leaving the true agglutination. The tube should be read macroscopically within 1 minute, and negative tubes should be checked rnicroscopi- cally, with care taken to compare them with the control. If the DPT is negative, then the SAT should be done. The RBCs should be washed twice in solution and an antiglobulin test performed with anti-IgG.
If both the DPT and the SAT are negative, then these tests should be repeated, first with LIM at its natural pH (4.5-4.9) and second with unwashed patient cells suspended in autolo-
Table 2. Modified DPT* method of testing
Reagents Positive Negative
Test control control
AB serum 2 drops 2 drops Diluted anti-D 2 drops 2-5% test red cells 2-5% 0 Rh-positive cells 1 drop 1 drop
1 drop
‘Direct Polybrene test.
816 OWEN AND HOWS TKANSFUSION Val. 30. No. 9-1990
gous serum or plasma, instead of the AB serum. The controls should be set up as previously described. The second step should be taken only when it is known that the serum antibody screen was negative.
IPT In some instances, we tested autologous serum and/or eluate
by IPT, using two methods. One was the conventional method that follows the same procedure as described for the DPT. In the second method, autologous serum or eluate is incubated for 1 hour with pooled group 0 screening cells (5 vol serum or eluate + 1 vol 5% cells) and washed four times, and the washed cells are tested as by the DPT. The second method proved to be more sensitive, but, as only a limited number were tested, we recommend that both methods be used when investigating a case of DAT-negative AIHA.
Results Although we carried out 121 DPT investigations, only 79
patients were fully evaluated by DAT and eluate testing. The results obtained in the 79 completed investigations are given below and in Tables 3 and 4.
Analysis of DAT-positive cases DAT positive for IgG or IgG with C3d, IgA, or IgM on
the RBC surface. Of the 44 patients who had a positive DAT due to IgG either alone or with C3d, IgA, or IgM on the red cell surface, 36 had a positive DPT, and 8 had a negative DPT (Table 3). Six of those with a negative DPT had a positive eluate test. In these patients, the DPT was less sensitive than either the DAT or eluate. Of the 2 patients who had a positive IgG DAT, but negative DPT and eluate, 1 was a patient who had clinical AIHA and had a warm autolysin in the serum, and the other was a patient with systemic lupus erythematosus whose DAT became negative on storage. In these 2 patients, both the DPT and the eluate test were less sensitive than the DAT.
The three patients in whom the DPT appeared to be more sensitive than the eluate had raised cold agglutinins and im- munoglobulin detectable by the DAT. It should be stressed that in all three cases, the cells had been washed at 37°C and had negative saline controls.
DAT positive for C3d or C3d and IgM. Eighteen patients were DAT positive because of C3d, either alone or with IgM on the RBC surface. Six of these patients had positive eluates, three due to IgG antibody and three due to IgM antibody; in two patients, IgM antibody was detectable in both the DAT
Table 3. Results in DAT*-positive and -negative patients:
Eluate-positive Eluate-negative
positive negative positive negative
correlation between DA T, DPTt, and eluate positivity
and by eluate testing, and in the other case, i t was very weakly detectable in the eluate only. Of these six patients, one, with IgG strongly detectable in the eluate, was negative by DPT and had only a very small amount of C3d detectable by the DAT. In this patient, the eluate method was far more sensitive than either the DAT or DPT in detecting IgG. A sample in- vestigated a month earlier had had a weak positive DAT with anti-IgG, but a negative DPT and a positive eluate test. Of the 12 patients with negative eluates, 1 had a positive DPT. In that patient, IgG could be detected by DAT and eluate test for the first time a year later.
Analysis of DAT-negative cases There were 17 samples from 16 patients with negative DATs
(Tables 3 and 4). DPT- and eluate-positive cases. One (#16) of the two pa-
tients with a positive eluate test and DPT had been referred to us as having DAT-negative AIHA. When first tested by us, the DAT was negative, and the DPT and eluate test were pos- itive. However, when we examined the patient again 1 month later, the DAT had become weakly positive due to IgG.
DPT- and eluate-negative cases. Of the nine patients who were DAT-, DPT-, and eluate-negative, three had no evidence of hemolysis; the other six had steroid-responsive, spherocytic, acquired hemolytic anemia. Two of these six had autoantibody detectable in the serum, one (#8) had a warm autohemolysin, and the other (#5), who had autoanti-Jkn,” later developed a positive DAT, eluate, and DPT. A third patient (#9) in this
TRANSFUSION 19M-Vol. 30, No. 9 POLYBRENE IN AIHA 817
category developed a positive DPT and IPT in the eluate after a reduction in steroids. When the steroids were increased again, both the DPT and the IPT became negative.
DPT-positive, eluate-negative cases. Of the six patients in whom the eluate and DAT were negative but the DPT was positive, two were referred from other hospitals as having probable AIHA; in one patient (#14), additional clinical de- tails were not available, and the other (#13) had alcoholic liver disease with reticulocytosis and anemia. One patient (#12) had steroid-responsive, spherocytic, acquired hemolytic anemia, a papain autoantibody in the serum, and a negative eluate even on IPT.
The remaining two patients had spherocytic acquired he- molytic anemia in pregnancy. One of these patients (#lo) had recurrent hemolysis in two pregnancies, with full recovery after delivery and steroid therapy. During her second pregnancy, the DPT was found to be positive on two separate samples, and an IPT on the eluate was also positive. The baby was born jaundiced but had a hemoglobin concentration of 17 g per L and responded to phototherapy. A cord sample from the baby was not suitable for serologic testing. A sample taken 1 week after birth had a negative DPT and DAT, but, when tested by the IPT, the eluate was positive, as was the eluate from a maternal sample received at the same time.
The other patient (#11) presented during her first pregnancy with AIHA and negative DAT, eluate, and serum screens. The DPT was positive, but both the eluate and serum were negative on the IPT. The patient was seen again 2 months later, at which time the DPT remained positive. She delivered a normal infant and, when seen several months after delivery, was well. The DPT at this time was still positive but much weaker than previously.
Discussion
This is the first comprehensive report comparing the DPT with DAT and eluate testing in the serologic in- vestigation of AIHA. An attempt is made to evaluate the results shown in Tables 3 and 4. For this analysis we applied the following definitions:
1. The DAT was regarded as positive if C3d alone, immunoglobulin alone, or both together were detected on the RBC surface.
2. The positive DPT included samples that were only weakly reactive or reactive only after testing by SAT.
3. Positive eluates were those that reacted by the pa- pain technique, the IAT, or both, but not those that re- acted on the IPT only.
From Table 3, it can be seen that, although there is a good correlation between immunoglobulin detected by either DAT or eluate and a positive DPT, in 20 (25%) of 79 patients, the DPT was less sensitive than the DAT, and in 7 (9%), it was less sensitive than the eluate. This discrepancy is partly due to the fact that the DPT does not detect the presence of complement alone on the RBC surface. As expected, all three cases of cold hemagglu- tinin disease (CHAD) were DPT negative, whereas the DAT was strongly positive because of C3d alone on the RBC surface. In contrast, in 4 (25%) of 12 non-CHAD cases of AIHA, in which C3d alone was detectable on
the RBC surface by the DAT, the DPT was positive. In 3 of these 4, IgG was detected in the eluate. This sug- gests that in these cases the DPT may have been a more sensitive indicator than the DAT of immunoglobulin on the RBC surface. There were also six cases of AIHA in which the DPT was positive when the DAT and eluate were both negative.
Further observations regarding the sensitivity of the manual Polybrene test were published by L a l e ~ a r i ' ~ in 1987. As most of our survey was carried out before that date, we did not include his modifications in our technique.
There are several reports comparing the efficiency of the IPT and standard serologic techniques in detecting RBC alloantibodies. Malde et al.4 found in a compre- hensive review of the IPT that, although 31 of 180 Rh system antibodies reacted only on the IPT and most other Rh system antibodies were enhanced, 10 Rh system an- tibodies failed to react by this technique. IAT-reacting, IPT-negative antibodies within the Kell, Duffy, and Kidd systems were sometimes detectable by the SAT, but sev- eral were not detected even by this technique.
Fisher' reported similar findings in a survey of 244 patients. Of 82 patients with Rh system antibodies, 7 antibodies were missed by the IPT and 19 were detect- able only by this test. All examples of anti-Jk" and -Fy" showed the same sensitivity on IPT as on low-ionic- strength solution anti-human globulin, 2 of 5 anti-Jka were detectable only by IPT, and all 20 anti-K were detectable by the SAT.
We conclude that, although the DPT is useful in eval- uating patients with suspected AIHA, particularly those with negative DATs and nonreactive eluates, i t should not be used as a substitute for the DAT or eluate testing. The main reasons for this are: 1) The DPT will not detect complement. 2) As already stated, there were several cases in which the DPT was less sensitive in detecting immunoglobulin than the DAT and/or the eluate. 3) The DPT does not distinguish the immunoglobulin class of the antibody. 4) The DPT should not replace eluate test- ing, as the latter is often necessary to determine the specificity of antibodies present. Definition of antibody
.specificity is particularly important when an underlying alloantibody is suspected.
However, because of its simplicity and rapidity, we have found the DPT a useful additional test in detailed investigation of patients with AIHA. It should be ern- phasized that the test frequently required repetition to ensure consistent results, and there is considerable var- iation in the results obtained with different modifica- tions, such as DPTversus SAT, different pH of the LIM, and addition of patient serum in individual cases. When negative results are obtained by the standard DPT tech- nique, the modifications described in this paper should be used.
818 OWEN AND HOWS TRANSFUSION
Vol. 30. No. 9-1990
Acknowledgments The authors thank K. Beddows and S. Edwards for technical as-
sistance and K. Druce for typing the manuscript.
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3. Ferrer Z, Wright J, Moore BPL, Freedman J. Comparison of a modified manual hexadrimethrine bromide (Polybrene) and a low- ionic-strength solution antibody detection technique. Transfusion
4. Malde R, Kelsall G, Knight RC. The manual low-ionic strength polybrene technique for detection of red cell antibodies. Med Lab Sci 1986;43:360-3.
5 . Fisher GA. Use of the manual Polybrene test in the routine hos- pital laboratory. Transfusion 1983;23:152-4.
6. Petz LD, Branch DR. Serological tests for the diagnosis of im- mune hemolytic anemias. In: McMillan R, ed. Methods in he- matology. New York. Churchill Livingstone, 1983:12-3.
8. Garratty G, Postoway N, Nance S, Brunt D. The defection of IgG on the red cells of “Coombs negative” autoimmunc hemolytic anemias (abstract). Transfusion 1982;22:430.
10. Dacie JV, Lewis SM. Practical haematology. 6th ed. New York: Churchill Livingstone, 1984.
11. Issitt PD, Issitt CH. Applied blood group serology. 2nd cd. Mal- vern, PA: Cooper Biomedical 1983.
12. Rubin HJ. Antibody elution from red blood cells. J Clin Pathol
13. Ganly PS, Laffan MA, O w e n I, Hows JM. Auto-anti-Jk” in Evans’ syndrome with negative direct antiglobulin test. Br J Haematol
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Irene Owen, FIMLS, Senior MLSO, Department of Hacmatology, Royal Postgraduate Medical School, Hammersmith Hospital, Du Canc Road, London W12 OHS, UK. [Reprint requests]
SYMPOSIUM ON THE CELLULAR AND MOLECULAR BASIS OF THE PLATELET STORAGE LESION
The symposium on the cellular and molecular basis of the platelet storage lesion, organized by the Yale University School of Medicine and sponsored by the National Heart, Lung, and Blood Institute and the American Association of Blood Banks, and held April 9-10, 1991 in Bethesda, Maryland is designed to stimulate inves- tigator-initiated research which will address fundamental questions concerning the etiology of the platelet storage lesion. A major goal is to provide a forum for platelet researchers in transfusion medicine, hematology and basic science to interact and share new ideas. The symposium will provide a review, by recognized leaders in the field, of various aspects of the cellular and molecular changes which occur in platelets during blood bank storage as well as in vivo, during activation. The content of the meeting will be at the intermediate to advanced level and there will be numerous opportunities for discussion and interaction among attendees. A consensus panel will convene on April 10, 1991 to summarize symposium highlights, discuss and expand on areas covered during the meeting and to identify, formulate, and recommend future research directions and initiatives.
For registration information contact: The Office of Postgraduate and Continuing
Yale University School of Medicine Room IE-53 SHM 333 Cedar Street New Haven, CT 06510
