Fish Immunology (1+1)

Unit 5- Specific defence mechanism in Fish

5.1.4. B cell activation
If B cell immunoglobulin receptor molecules are crosslinked by foreign antigen and its IL-1 and IL-4 receptors are stimulated, the B cells are activated and express new class II MHC antigen. The membrane receptors for antigen are concentrated at a particular position on the surface of the B cells. The B cells divide repeatedly to form antibody-secreting plasma cells and memory cells. These plasma cells are widely distributed throughout the body but concentrated in the head kidney and spleen of fish. The plasma cells usually die after 3-6 days of secretion and the immunoglobulin levels in the serum decline gradually. The second populations of cells derived from antigen- sensitive B cells and morphologically indistinguishable from parent cells are known as memory cells.

The interactions between an antigen-presenting cell, a B cell and a T-helper cell that lead to the activation of B cell and development of memory cells and antibody-producing plasma cells.