Antibody Mediated Imminity Response-B cell

-B cells are formed in bone marrow and usually matures in lymph nodes or in blood circulation.
-The B cells matures by forming B cell receptors.
-B cells receptor are formed by attachment of antibodies to plasma membrane with the antigen binding sites facing outwards.
-The B cells migrate to blood circulation until it encounters pathogen that have complementary antigen with its B-cell receptor.
-Phagocytosis of the pathogen occurs.
-The pathogens are broken down into smaller pieces known as antigen by action of hydrolytic enzyme..
-The antigens are attached to MHC to form antigen-MHC complex on the outer surface of plasma membrane.

-The B cell then attaches to Th cell that has complementary TCR with its antigen-MHC complex.
-The attachment occurs between antigen-MHC complex of B cell with TCR of Th cell.
-In this process, B cell acts on antigen presenting cell (APC).

-The T cell secrete INterleukin 2 (IL2).
-The Th cell divides to form memory cells and large number of effector Th cells which secrete more IL2.
-IL2 stimulate the B cells to divide through mitosis to form memory cells and large number of plasma cells/effector B cells.
-Plasma cells secrete large quantity of antibodies into blood circulation.
-The antibodies are then used to attack and destroy specific type of antigen in body.

-Eg of antibody action are antitoxin, complement fixation, opsonisation, precipatation and agglutination.