B Lymphocytes Humoral Immunity And Provides Defense...

Introduction : B lymphocytes are the effectors of humoral immunity and provides defense against pathogens by producing antibody. B cells constitute approximately 15% of peripheral blood leukocytes and arise from progenitors and precursors in the bone marrow. B lymphocytes undergo random immunoglobulin variable gene rearrangements at the heavy and light chain loci. These chains pair with the IgÃŽ ± and IgÃŽ ² polypeptides to form the mature B-cell receptor which is then transported onto the cell surface where it can bind antigen and signal inside the cell. Different populations of B cells result in pre immune pools where each cell in these quiescent populations expresses a B cell antigen receptor with a unique specificity. The BCRs come in contact with their specific antigen and generate several intracellular signals are which leads activation, differentiation, and formation of plasma cells and memory B cells. This process mediates the response to subsequent antigen challenges. B lymphocytes play an essential role by not only producing antibodies but also functioning as antigen-presenting cells and certain B cells can also negatively regulate the immune response by producing regulatory cytokines and directly interacting with pathogenic T cells via cell to cell contact. Newly generated immature B cells are selected to enter the peripheral mature B-cell pool only if they do not bind to self-antigen. Immature B cells that bind to self antigen are not generally recruited to matureShow MoreRelatedThe Main Functions Of The Immune System907 Words   |  4 PagesDefending the host against pathogens and toxins is the major function of the immune system, a task essential to any organism. Composed primarily of individual cells rather than forming into organs, the cells of the immune system spread throughout the body. The immune system is able to distinguish its own molecules from foreign molecules. 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