Fish Immunology (1+1)

Unit 7- Lymphocytes

7.2. B-cells
B cells are primarily responsible for specific humoral immunity (relating to antibodies).These B cell in the presence of antigen are activated and differentiated into plasma cells in spleen, after differentiation Plasma cells migrate to the head kidney. These B cells are characterized by the expression of B cell receptor, a surface immunoglobulin receptor (sIG). B cells of teleost fish are highly phagocytic and display microbicidal properties. In case of intestine there is an increase in number of IgM+ cells from the anterior and middle to the posterior part of the intestine because the higher absorption of antigens is present in posterior part of gut. In skin of fish, B cells are present only in the epithelium layer and the numbers of IgM-secreting cell present in the skin can increase up to 20-fold if the fish is immunized with antigen. B cells are also present in the stratified epithelium of the gill arch and filaments.