IN 1 1..kNAlION^i01114NAI 01 LLPROS)^

Volume 48, Number 4Printed in the U.S.A.

INTERNATIONAL JOURNAL OF LEPROSYand Other Mycobacterial Diseases

OFFICIAL ORGAN OF THE INTERNATIONAL LEPROSY ASSOCIATION

EDITORIAL AND PUBLICATION OFFICE

USPHS Hospital

Carville, Louisiana 70721, USA

VOLUME 48, NUMBER 4^

DECEMBER 1980

EDITORIALS

Editorial opinions expressed are those of the writers.

Thoughts on the Immunology of Leprosy

Leprosy is a disease produced by My-cobacterium leprae, a seemingly obligateintracellular pathogen. M. /eprae has aslow growth, and most of it takes place in-side tissue macrophages. This, and the na-ture of its cell wall are key concepts. Asskin and peripheral nerves are preferential-ly attacked, lesions are accessible to clini-cal and pathological examination. M. lep-rue does not grow in vitro: its exactidentification has been based mostly onnegative properties. Obtainment of anti-gens and their identification is difficult andis further hampered by the need of elimi-nating contaminating host tissue compo-nents. Another important concept is thecurrent lack of a fully adequate languageand sufficient knowledge to fully explainimmunological events in leprosy. Great ad-vances have been made, but a lot remainsto be learned. Imagine the situation in 1940when high resistance to M. leprue and lowantibody levels in tuberculoid leprosy (andthe opposite situation in lepromatous lep-rosy) had to be explained in the absence ofconcepts such as those of cellular immu-nity, role of lymphocytes, macrophage ac-tivation, or lymphokines. Our current ef-forts may be looked upon with similar eyesin 1990.

There are four aspects that will be men-tioned here:

a) Relationship of immunology to clini-cal and histologic features of leprosy.

b) Vaccination and leprosy.c) Immunology and reactional states.d) Immunology and diagnosis of M. lep-

rue and leprosy.

It is increasingly common to accept theidea that leprosy is a disease with diverseclinical types constituting a spectrum. Itgoes from the relatively highly resistanttuberculoid leprosy to the low resistanceform of lepromatous leprosy. There are in-termediate forms. Patients are usually sta-ble, but there are ways by which they maymove along the spectrum. Clinical formshave corresponding histologic features.The main point of the latter is that epithe-lioid cells and an admixture of lymphocytesindicate resistance whereas foamy histio-cytes and no lymphocytes (except duringreactional states) indicate lack of resis-tance'. Clinical and histologic features arereflections of the immune status of the pa-tient. Resistant individuals are able to de-velop cell-mediated immunity to M. /epraeas witnessed by a positive Mitsuda reactionand mitogenesis and lymphokine produc-tion when their lymphocytes are incubated

' Ridley, D. S. Histological classification and theimmunological spectrum of leprosy. Bull. WHO 51(1974) 451-465.

435

436^ International .1011,71(11 of Leprosy^ 1980

with M. /epray or its fractions. This doesnot happen with lepromatous patients ortheir lymphocytes.

Antibody production does not seem to heinvolved directly in resistance becausehigher levels of them occur in lepromatouspatients. It must he admitted, however,that we know little about the nature of an-tibodies that occur in LL, particularly towhich structural components of the bacillithey are directed against.

There is growing evidence that leproma-tous patients do not necessarily have anoverall impairment of cell-mediated immu-nity (CMI) 2 •"• ". Reports are not unani-mous, but the truth seems to he that what-ever overall impairment of CM! exists, it issecondary to the disease, either related tofactors present in any chronic disabling dis-ease (undernutrition, overcrowding, para-sites) or by factors such as replacement oflymphoid tissue by granulomatous struc-tures and blocking of lymphocyte circula-tion. This overall impairment may not oc-cur in a given patient, or it may he of lowintensity. It usually disappears when thegeneral state of health improves and/orwhen bacillary load is diminished or wipedout by therapy. In contrast, anergy towardsM. /ep•ay (as measured by the tests em-ployed), is persistent, and it may antedatethe appearance of clinical disease'. Wheth-er or not it may precede contact with Al.leprae is a critical and unanswered ques-tion. The fate of M. leprae and of the pa-tient is decided inside macrophages. Mac-

• Bullock, W. E. Leprosy: A model of immunolog-ical perturbation in chronic infection. J. Infect. Dis.137 (1978) 341-354.

• Faber, W. R., Leiker, D. L., Nengerman, I. M.,Zefilemaker, W. P. and Schellekens, P. Th. A. Lym-phocyte transformation test in leprosy: Decreasedlymphocyte reactivity to Mycobacterium leprae inlepromatous leprosy, with no evidence for a general-ized impairment. Infect. Immun. 22 (1978) 649-656.

' Rea, T. H., Quismorio, F., Harding, 13., Friou, G.and Levan, N. Quantitative dinitrochlorohenzene(DNCB) responsivity and phytohemagglutinin (PHA)induced lymphocyte transformation in patients withlepromatous leprosy. Int. J. Lepr. 44 (1976) 250-255.

' Ulrich, NI., Salas, B. and Convit. J. Lymphocytetransformation with phytomitogens in leprosy. Int. J.Lepr. 40 (1972) 4-9.

Price. NI. A., Enders, E. M., Anders, R. F., Rus-sell, D. A. and Dennis, E. S. Cell-mediated immuno-logic status of healthy members of families with a his-tory of leprosy. Int. J. Lepr. 43 (1975) 307-313.

rophage control by lymphocytes seemed tobe a single road a few years ago. It is notquite so any more. Macrophage function isaffected by lymphokines, but macrophagesmay act on lymphocytes in diverse ways,not only by digestion and/or presentation ofantigenic determinants in their surface, butalso by many other means not always clear-ly understood 7 • 8 . There is also evidence ofcontrol of macrophage and lymphocytefunctions by scrum factors attached or notto the surface of the macrophages and al-tered by them. The role of polymorphonu-clear leukocytes, while not explored, hasnot been ruled out.

Another point, and an important one, isthat lymphocyte populations are being sub-divided more and more. The T, 13 and nullclassification is not sufficient any more.The exact pairing of lymphocyte receptors,lymphocyte types, and lymphocyte func-tions in man has not been achieved yet"• ".

Control mechanisms are exceedingly im-portant. The coincidence of low resistance,low levels of certain aspects of cell-mediat-ed immunity, and high levels of (some) an-tibodies that may also modulate granuloma-tolls responses is too common in certainclinical forms of intracellular and othergranulomatous infections to he accidental.This occurs in certain forms of coccidioi-domycosis, schistosomiasis, leishmaniasis,and paracoccidioidomycosis, to name buta few"• 15• I" . The very detailed clin-

Allison, A. C. Mechanisms by which activatedmacrophages inhibit lymphocyte responses. Immunol.Rev. 40 (1978) 3-27.

' Unanue, E. R. The regulation of lymphocyte func-tions by the macrophage. Immunol. Rev. .40 (1978)227-255.

" Chess, L. and Schlossman, S. F. Human lympho-cyte subpopulations. Adv. Immunol. 25 (1977) 213-241.

1 " Snell, G. D. T cells, "1 . cell recognition structuresand the major histocompatibility complex. Immunol.Rev. 38 (1978) 3-69.

" Boros, D. L. Granulomatous inflammations.Prog. Allergy 24 (1978) 183-267.

1 ' Fava-Netto, C. The immunology of South Amer-ican blastomycosis. Mycopathol. Mycol. Appl. 26(1965) 349-358.

1 " Fava-Netto, C. The serology of paracoccidioido-mycosis. Present and future trends. In: Paracoccid-ioidom•cosis. Proceedings of the First l'an AmericanSvmposium (11101W110), .Medellin, Columbia. PAHOScientific Publication No. 254. Washington: PanAmerican Health Organization, 1972, pp. 209-213.

" Goihman-Yahr, M., Convit, J. and I'inardi, M. E.

48, 4^ Editorial.s.^ 437

ico-pathological analysis done in leprosyTay not be easily achieved in diseases thatalso attack organs not as readily accessibleas the skin, but the main features are there.The basic derangement of the immune sys-tem ought to he the same in all correspond-ing clinical forms of the diseases men-tioned, but it is specific in that it applieswily to a given causative organism (e.g.,patients with diffuse allergic leishmaniasismay develop a positive lepromin reactionand may he resistant to leprosy). In otherwords, the phenomenon may be better ex-plained not by a passive allergy but by anactive one where the antigen or organismis specifically recognized by certain lym-phocyte populations that act in a suppres-sive way''''s. A more precise explanationwill have to wait for more knowledge.

The immune response is geneticallyruled. Efforts have been made to charac-terize genetic markers that would identifylepromatous patients. Current emphasishas been based on knowledge obtainedfrom mice. In these animals there is a rel-atively well known relationship between Irgenes and the MHC. Initially, the effortwas directed to find the "formula — of thelepromatous patient expressed in H LA an-tigens; this was not too fruitful. Anotherway is to establish an "H LA formula — thatwould reflect a genetic composition suchthat patients would react in a given way("weak responders — ) not only in leprosybut in other diseases, i.e., a genetically-de-termined, HLA-expressed overall patternof reaction. This is intellectually more sat-isfying, but no conclusive results are avail-able. The human system is very complex;it is not impossible that different antigenicformulae may apply to different ethnic

Aspectos inmunokigicos en la Leishmaniasis. An.tarns. Derr. 52 (1977) 325-332.

" Phillips, S. M. and Colley, D. G. Immunologicaspects of host responses to schistosomiasis: Resis-tance, immunopathology and eosinophil involvement.Prog. Allergy 24 (1978) 49-182.

'" Swatek, F. E. The epidemiology of coccidioido-mycosis. hi: life Epidemiology of Iltonon

Di■ease.s. Al-Doory, l'. ed. Springfield, Illinois:Charles C Thomas, 1975, pp. 74-102.

' 7 Eichmann, K. Expression and function of idio-types in lymphocytes. Adv. Immunol. 26 (1978) 195-2_54.

Turcotte, R. Suppressor cells in experimentalmurine leprosy. Int. J. Lepr. 46 ( 1978) 358-363.

groups. The code may be redundant anddegenerate, and there is further complicat-ing evidence that resistance to intracellularparasites and development of delayed hy-persensitivity (as measured by intradermaltesting) may he coded by different genes indifferent loci'' 2". 21 ' 22 ' 2" ' 21 ' 21'

My feeling is that there will not be founda genotype such that it would definitelycondemn somebody to become leproma-tous if he or she contacts M. hproe. Wemay find one that would favor a given typeof response under a given set of circum-stances. Vaccination against leprosy is con-ceivable only if this second alternative istrue. In a rational world, one would startresearch on vaccination only when factorsthat determine immune response are wellknown. This is not the story of successfulvaccines, however. Current efforts in lep-rosy vaccination mainly aim at the use ofkilled M. leprae together with adjuvantsapplied to nonlepromatous individuals toinduce a preemptive immune response orto channel it towards a desirable goal. Thesubject has been covered in several author-itative reviews 2 s• 2 "• 3". My point is that the

'" Greiner, J., Schleiermacher, E., Smith, 1., Len-hard, V. and Vogel, V. The III.A system and leprosyin Thailand. Hum. Genetics 42 (1978) 201-213.

2" Najakima. S., Kobayashi, S., Nohara, NI. andSato, S. 111.A-antigen and susceptibility to leprosy.Int. J. Lepr. 45 (1977) 273-277.

21 Nakamura, R. M. and Tokunaga, T. Strain dif-ference of delayed-type hypersensitivity to 13CG andits genetic control in [nice. Infect. Immun. 22 (1978)657-664.

.22 Poulter, L. W. Systemic immunological reactivityin the absence of delayed-type hypersensitivity duringmurine leprosy. Cell. Immunol. 46 (1978) 117-127.

2 '` Rea, T. IL, Levan, N. E. and Terasaki, P. I. His-tocompatibility antigens in patients with leprosy. J.Infect. Dis. 134 (19761 615-618.

Skamene, E., Kongshauvn, I'. A. L. and Sachs,D. H. Resistance to Le/Ater/a monorytoccuc■ in mice:Genetic control by genes that are not linked to the 11 2_-complex. J. Infect. Dis. 139 (1979) 228-231.

2 ' Stoner, G. I.., louw, J., Belehu. A. and Naafs,13. In vitro lymphoproliferative response to llycobac-

Icrium leproe of 111,A-D identical siblings of lepro-matous leprosy patients. Lancet 2 (1978) 543-547.

' " Stoner, G. L. Ir genes and leprosy. Int. J. Lepr.46 (19781 217-220.

Takada, Sada, M., Ozaw•i S Seikiguchi,S. FILA and mycobacterial infection: Increased fre-quency of I3-8 in Japanese leprosy. Tissue Antigens11 (1978) 61-64.

▪ Convit, J. and Ulrich, M. General ideas concern-ing a vaccine against leprosy: A basis for discussion

438^ International Journal of Leprosy^ 1980

number of possible ways is great, favorableresults may or may not he achieved, andintensity of efforts will depend on the avail-ability of funds and on whether a very ef-fective, easy to give, and cheap chemo-therapeutic agent(s) becomes available inthe future. Among other avenues of vaccineresearch we could mention the use of at-tenuated live preparations of M. leprue orof other related mycohacteria that wouldcritically cross-react with M. leprue.Everything depends on the knowledgeabout antigenic components and chemicalconstitution of mycohacteria and on devel-opment of methods to inoculate M. /eproein animals and to grow these bacilli in vitro.This last is the most important hurdle toovercome.

At the beginning, I stressed the impor-tance of the cell wall: it is antigenically andchemically related to the cell wall of othermycohacteria and acid-fast organisms. It isthis cell wall that gives M. leprue the prop-erty of adjuvanticity and that may explainmany features of reactional states, evenmaybe their existence. Reactional statesare not necessarily present in other intra-cellular diseases immunologically akin tolepromatous leprosy (diffuse anergic leish-maniasis, for instance). Without delvinginto this subject I would like to point outthe following:

a) Tissue damage may be produced bydiverse mechanisms reciprocally re-lated or not.

b) Adjuvanticity also implies immunedeviation.

c) Autoantihodies, cytotoxic or not, maybe induced by M. /eprac cell wallsacting as adjuvant.

d) Explanation of reactional states solelyby humoral factors (circulating im-mune complexes and/or Arthus phe-nomenon) is at best incomplete"', and

during the Eleventh International Leprosy Congress.(editorial) Int. J. Lepr. 46 (1978) 61-63.

1 " Godal, T. The rationale behind a leprosy vaccineresearch program. Int. J. Lepr. 45 (1977) 61-63.

" Godal, T. Is immunoprophylaxis in leprosy fea-sible? Lepr. Rev. 49 (1978) 305-317.

31 Tung, K. S. K., Kimi, 13., I3jorvatn, B., Kronvall,G., McLaren, L. C. and Williams. R. E. Discrepancybetween Cly deviation and Raji cells tests in detectionof immune complexes in patients with leprosy. J. In-fect. Dis. 136 (1977) 216-221.

adjuvant disease of the rat may pro-vide a better model for study" 2 •" 3 . Onthe other hand, the Ludo phenome-non may he better explained by hu-moral factors:".

Tissue damage in reactional leprosy mayhe due to activation of some lymphocytepopulation by cell walls of Al. /eprae.These lymphocytes may directly induce tis-sue damage or else they may liberate sol-uble factors that could induce the appear-ance and activation of cells of the granulo-cytic series.

Immunological methods have been usedfor the diagnosis of disease and of subclin-ical infection since the dawn of bacteriol-ogy. Several roads may he taken, and theyare not mutually exclusive. One is the useof an intradermal test to detect delayed hy-persensitivity to a given set to antigens.Sensitivity would he present in patientswith leprosy or individuals sensitized to thebacillus. This road is a priori feasible be-cause it has been successfully used in othermycohacterial diseases such as tuberculo-sis and because M. leprae induces mito-genesis in vitro in lymphocytes from per-sons with the disease or presumablysensitized to M. leprue. As resistance anddelayed hypersensitivity may not he me-diated by the same cell population, it doesnot necessarily follow, although it is likely,that an intradermal test would he negativein lepromatous patients. The problem is thelack of an appropriate antigenic prepara-tion. The likely sources would he proto-plasmic fractions from armadillo-grown M.leprac or from cross-reacting mycohacte-ria. The technical problems are great, and

" 1 Goihman-Yahr, M., Requena, M. A., Vallecalle-Suegart, E. and Convit. J. Autoimmune diseases andthalidomide. II. Adjuvant disease, experimental al-lergic encephalomyelitis and experimental allergicneuritis of the rat. Int. J. Lepr. 42 (1974) 266-275.

"" Goihman-Yahr, M.. Convit, J., Rodriguez-Ochoa,G., Aranzazu, N., Villalba-Pimentel, L., Ocanto, A.and GOmez, M. E. Significance of neutrophil activa-tion in reactional lepromatous leprosy. Effects of tha-lidomide in vivo and in vitro. Activation in adjuvantdisease. Int. Arch. Allergy Appl. 'ninlioo]. 57 (1978)317-332.

"' Quismorio, F. P., Rea, T., Chandor, S., Levan,N. and Friou, G. Lucio's phenomenon: An immunecomplex deposition syndrome in lepromatous leprosy.Clin. Immunol. Immunopathol. 9 (1978) 184-193.

48, 4^ Editorials^ 439

I do not foresee short-term breakthroughsin this respect.

The use of antibodies for diagnosis de-pends on the individualization of an anti-gen-antibody reaction characteristic of lep-rosy and 111. leprac and not occurring withother related organisms (mycobacteria)with which contact may be likely. Theproblem here is not lack of antibody re-sponse in all forms of leprosy or in methodsto detect this but rather in lack of a definiteor specific antigen. This specific antigenneed not be related to antigens involved inresistance or in adjuvanticity. There issome evidence that a protein antigen maybe specific to AL leprae'."". Its isolationneeds an adequate supply of unaltered or-ganisms from armadillos or else the cultureof M. /eprae in vitro.

In summary, the main avenues for pro-gress would be:

a) A more accurate definition of immu-nologically active cells; this includestheir characterization by reliablemethods and understanding of theirfunctions and of control mechanisms.

b) A better insight of adjuvants. Thiswould include knowledge of theirchemical structure and understandingof the way by which they act.

' Caldwell, H. I). and Buchanan, F. M. Immuno-chemical and structural integrity of surface proteinantigens of mycobacteria during separation from ar-madillo liver tissue. Int. J. Lepr. 47 (1979) 469-476.

" Caldwell, H. D., Kirchheimer, W. F. and Bu-chanan, T. M. Identification of a Mycobacterium hp-roe specific protein antigen(s) and its possible appli-cation for the serodiagnosis of leprosy. Int. J. Lepr.47 (1979) 477-483.

c) Obtainment of antigens from M. hp-roc and their immunological andchemical characterization.

d) If all or most of the above is achieved,then manipulation and direction of theimmune response is possible. Currentreports of the use of cyclophospha-mide to eliminate suppressor lympho-cytes"' and of indomethacin to sup-press their function are examples ofthis. All this may be far from us.

I would like to point out that the prob-lems that we face are basically identical tothose of the immunology of cancer and ofautoimmune disorders. It is not that re-search in leprosy is not up to the times andcannot answer pertinent questions; it is thatthe questions now posed are key biologicalquestions not completely answered by any-one.

—Mauricio Goihman-Yahr

Acknowledgements. Work in our laboratory is sup-ported in part by grants from the Consejo de Desar-rollo Cientifico y Humanistico, Universidad Centralde Venezuela, and Consejo Nacional de Investiga-ciones Cientificas y TecnolOgicas, Venezuela (CONI-CIT proyecto S1-1074). An earlier version of this pa-per was read in the Symposium on Leprosy and otherMycohacterial Diseases (Antar Padilha-Goncalves,M.D., Chairman) at the Fourth World Congress of theInternational Society of Tropical Dermatology, NewOrleans, Louisiana, U.S.A., September 1979.

"' Glaser, NI. Regulation of specific cell-mediatedcytotoxic response against SV-40-induced tumor as-sociated antigens by depletion of suppressor T cellswith cyclophosphamide in mice. J. Exp. Med. 149(1979) 774-779.

Information Requested from NationalLeprosy Associations

The News & Notes section of the JOUR-NAL affords an opportunity for the readerto be made aware of activities of interest toleprosy workers throughout the world. ThePresident of the ILA, Professor Michel F.Lechat, has recently made available to usa list of over three dozen national leprosyassociations. By comparing this list with

recent items of News & Notes, it becomesclear that the readers of the JOURNAL donot have the opportunity of knowing aboutmany of these organizations. Even the larg-er organizations are known by name only,with little appreciation for the scope of theiractivities.

In an effort to remedy this situation and