Antibody The basic structure of antibody molecules it

Antibody: The basic structure of antibody molecules, it has a 4 chain structure, 2 identical heavy chain (H) and two identical light chain (L) held together in a loop by disulphide bond. the H and L chains include the antigen binding site and constant region.

Classification of immunoglobulin according to the variation in constant heavy chain : There are 5 major classes of Igs: 1. Ig. G (Gamma immunoglobulin) There are 4 subclasses (Ig. Gl, Ig. G 2, Ig. G 3, Ig. G 4). It is the only Ig. G that passes from the mother to the fetus. So produce passive immunization. It is representing (75 -80%) Of Igs in serum

It is not synthesized in fetal life. It is can activation complement throw classical pathway. It is long life spin (30 -35)days. Represented secondary immune response, so Ig. G is the most abundant Ig in serum & also in intracellular fluid. 2. Ig. M: It is th largest one of immunoglobulin, t is pentamer. It is the first Igs appear after immunization (primary immune response).

Life spin (5 -7)days. It is only the Ig that synthesized during fetal life. It is important in defense against bacteria &viruses. The main Ig produced early in the primary I. R. because 1 g. M present on the surface of B cells. 3. Ig. A (Alpha Immunoglobulin) It is a secretary type of immunoglobulin found in different secretion such as saliva, milk, tears & the secretion of the respiratory system, intestinal genital tract.

It is protect mucus membrane from attack by bacteria & virus infection It is usually found as dimer (2 units) cause neutralizing for virus infection. 4. Ig. D: Acts as Ag receptors when present on the surface of certain BLymphocyte. Found in very small amount in serum.

5. Ig. E: It is produced by plasma cell, but taken by specific Ig. E receptors on mast cell (in tissue) & in basophile in serum. Ig. E usually found in small amount in serum body fluid. mainly against parasite infection & causing increase permeability that lead to inducing chemo tactic by degranulation.

Mechanism of immune response: There are two types of immune response , primary immune response in which characterized by predominant of IGM , low antibody titer with short time and present of lag phase ( lag phase is the period of time that required to sensitized immune response. While secondary immune response more active with long time and predominant of IGM without lag phase, also characterized by present of memory cells.

Antibody tittered A nt ib o d y tit te re d

Anatomy of immne system Stem cells of immune system generally originated from tolk sac in first six weeks of gestation , then liver takes this function till 12 months after that bone marrow will take this function at origination and proliferation of stem cells which are renewal cells. primary lymphoid organ ( central lymphoid tissue ): the first organ for maturation and proliferation of T-lymphocyte is thymus , while the first organ of maturation and proliferation of B-lymphocyte is still unknown.

seconday organ (peripheral lymphoid tissue ) : that include lymph nodes, spleen , tonsil , mucosa associated lymphatic tissue (MALT).

Bone marrow generate stem cells erythroid Lymphoid Myeloid lymphocyte platelet RBC Large granular Natural cell basophile mylocytes eosinophile Small granular Killer cell T-lymphocyte neutrophile B-lymphocyte monocyte macrophage

Difference between t and B cells: character T-cells B-cells presence of peripheral blood 65 -80 8 -15 antigenic recognized surface immunoglobine T-cell receptor co 3 ++ ++ - other marker Cd 2, cd 3 , cd 4, cd 8 , cd 25 Cd 19 , cd 27 , cd 40 , cd 45 MHE Class II ++ ++ in activated Tcell ++ ++