ImmunityImmunity

Dr Mulazim Hussain BukhariDr Mulazim Hussain Bukhari

MBBS,DCP,MPhil,FCPS,PhDMBBS,DCP,MPhil,FCPS,PhD

IntroductionIntroductionThe defense system of the body against The defense system of the body against any injurious stress is called immune any injurious stress is called immune systemsystem

Te stress may be intrinsic (inside of the Te stress may be intrinsic (inside of the body) or extrinsic (out side of the body)body) or extrinsic (out side of the body)

Antigen: is any substance that elicits an Antigen: is any substance that elicits an immune response, from a virus to a sliver.immune response, from a virus to a sliver.

Antibody: Proteins secreted by the Antibody: Proteins secreted by the Lymphocytes in response to antigenLymphocytes in response to antigen

Features of immune systemFeatures of immune systemantigen-specific:antigen-specific: they recognize they recognize and act against particular antigens and act against particular antigens Systemic:not confined to the initial Systemic:not confined to the initial infection site, but work throughout infection site, but work throughout the body), and have the body), and have Memory:recognize and mount an Memory:recognize and mount an even stronger attack to the same even stronger attack to the same antigen the next time antigen the next time

Fluid Systems of the BodyFluid Systems of the Body

PlasmaPlasma

LymphLymph

BloodBlood

The 5 liters of blood of a 70 kg (154 lb) person The 5 liters of blood of a 70 kg (154 lb) person constitute about 7% of the body's total weight. constitute about 7% of the body's total weight. The blood flows from the heart into arteries, The blood flows from the heart into arteries, then to capillaries, and returns to the heart then to capillaries, and returns to the heart through veins.through veins.Blood is composed of 52–62% liquid plasma Blood is composed of 52–62% liquid plasma and 38–48% cells. and 38–48% cells. The plasma is mostly water (91.5%) and acts The plasma is mostly water (91.5%) and acts as a solvent for transporting other materials as a solvent for transporting other materials (7% protein [consisting of albumins (54%), (7% protein [consisting of albumins (54%), globulins (38%), fibrinogen (7%), and assorted globulins (38%), fibrinogen (7%), and assorted other stuff (1%)] and 1.5% other stuff). other stuff (1%)] and 1.5% other stuff). Blood is slightly alkaline (pH = 7.40 ± .05) and Blood is slightly alkaline (pH = 7.40 ± .05) and a tad heavier than water a tad heavier than water (density = 1.057 ± .009).(density = 1.057 ± .009).

Cells of the bloodCells of the blood

erythrocyteserythrocytes (red blood cells or RBCs), (red blood cells or RBCs),

leukocytesleukocytes (white blood cells or (white blood cells or WBCs), and WBCs), and thrombocytes thrombocytes (platelets).(platelets).

The leukocytes are further subdivided The leukocytes are further subdivided into into granulocytesgranulocytes (containing large (containing large granules in the cytoplasm) and granules in the cytoplasm) and agranulocytesagranulocytes (without granules). (without granules).

LeukocytesLeukocytesThe granulocytes consist of The granulocytes consist of – neutrophils (55–70%), neutrophils (55–70%), – eosinophils (1–3%), and eosinophils (1–3%), and – basophils (0.5–1.0%). basophils (0.5–1.0%). The agranulocytes are The agranulocytes are lymphocyteslymphocytes (consisting of B cells and T cells) and (consisting of B cells and T cells) and monocytesmonocytes. . Lymphocytes circulate in the blood and Lymphocytes circulate in the blood and lymph systems, and make their home in lymph systems, and make their home in the lymphoid organs. the lymphoid organs.

Normal Adult Blood Cell CountsNormal Adult Blood Cell Counts

Red Blood CellsRed Blood Cells 5.0*105.0*1066/mm/mm33   

PlateletsPlatelets 2.5*102.5*1055/mm/mm33   

LeukocytesLeukocytes 7.3*107.3*1033/mm/mm33   

   NeutrophilNeutrophil    50-70%50-70%

   LymphocyteLymphocyte    20-40%20-40%

   MonocyteMonocyte    1-6%1-6%

   EosinophilEosinophil    1-3%1-3%

   BasophilBasophil    <1%<1%

LymphLymphLymph is an alkaline (pH > 7.0) fluid that Lymph is an alkaline (pH > 7.0) fluid that is usually clear, transparent, and colorless. is usually clear, transparent, and colorless.

It flows in the lymphatic vessels and It flows in the lymphatic vessels and bathes tissues and organs in its protective bathes tissues and organs in its protective covering. covering.

There are no RBCs in lymph and it has a There are no RBCs in lymph and it has a lower protein content than blood. lower protein content than blood.

Like blood, it is slightly heavier than water Like blood, it is slightly heavier than water (density = 1.019 ± .003). (density = 1.019 ± .003).

: IgG-76%, IgA-15%, IgM-8%, IgD-1%, and IgE-0.002%

(a) complement fixation (proteins attach to antigen surface and cause holes to form, i.e., cell lysis), (b) neutralization (binding to specific sites to prevent attachment—this is the same as taking their parking space), (c) agglutination (clumping), (d) precipitation (forcing insolubility and settling out of solution), and other more arcane methods.