Humoral immunity

Humoral immunity

The humoral immune response begins with the recognition of antigen. Though the classification separates the cell mediated and humoral immunity with different cell types they do interact to bring an effective immune response. Specific T-cells are stimulated to produce lymphokines that are responsible for the antigen-induced B-cells proliferation and differentiation.

This is for the T depended antigens. However some of the macro antigenic molecules can directly stimulate the B cells directly. Through a process of clonal selection specific B-cells are stimulated, the activated B-cell first develops into a B-lymphoblast, becoming much larger and shedding all surface immunoglobulin. This terminal differentiation stage is responsible for production of primarily IgM antibody during the primary immune response. Few newly differentiated B-cells remain as long-lived “memory cells” without secreting antibodies. Upon subsequent encounter with antigen, these cells respond very quickly to produce large amounts of IgG, IgA or IgE antibody, generating the better secondary immune response.

Pathogen or foreign protein + Macrophage / dentritic cells → processed antigen

The initial differentiation step that ultimately leads to the mature B-cell involves DNA rearrangements in heavy chain variable (V) region as well as similar rearrangements within the light chain genes to synthesis immunoglobulin. These stages are, of course, initiated upon encounter with antigen and activation by T-helper cell to secrete lymphokines. The activated B-cell first develops into a B-lymphoblast, becoming much larger. IgM antibody is formed during the ‘primaryimmune response.’ Instead, these cells undergo secondary DNA rearrangements tomodify the constant region and forms IgG, IgA or IgE antibodies during secondaryimmune response. The suppressor T-cells suppresses the immune response oncean adequate amount of antibody formed. Another way of suppression occurs by the produced antibody itself and known as, “antigen blocking”. When high doses of antibody interact with the entire antigen’s epitopes thereby inhibits interactions with B-cell receptors.