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 immunoglobulinaccording to the variation in constant heavy chain : • There are 5 major classes of Igs: • 1. IgG (Gamma immunoglobulin) • There are 4 subclasses (IgGl,IgG2,IgG3,IgG4). • It is the only IgG 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 IgG is the most abundant Ig in serum & also in intracellular fluid. • 2. IgM: • 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 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 1gM present on the surface of B cells. • 3. IgA (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. IgD: • Acts as Ag receptors when present on the surface of certain B-Lymphocyte. • Found in very small amount in serum.
5. IgE: • It is produced by plasma cell, but taken by specific IgE receptors on mast cell (in tissue) & in basophile in serum. • IgE 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 immuneresponse , 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 Antibody tittered
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 mylocytes platelet RBC Large granular Small granular Natural cell Killer cell T-lymphocyte B-lymphocyte basophile eosinophile neutrophile monocyte macrophage