Linfocitos B

Abstract

The B-cell antigen receptors (BCR) make it possible to recognize and respond to the antigens, initiating a program of proliferation and differentiation in immunoglobulin secreting plasma B cells or antibodies, which are secreted forms of BCR that neutralize the pathogen. The BCR also permits the memory B cell to be reactivated by the antigen in the secondary or recall immune responses. The B cells integrate the information received through the BCR with that of other co-receptors and receptors of co-stimulators and inhibitors, to produce different types of cell responses. These include deletion, activation, proliferation and cellular differentiation. B cells are developed in the bone marrow. Their precursors rearrange the genes that code for the heavy and light chain of the BCR. Once the B cell produces its antigen receptor, if it is auto-reactive, the reprogramming or negative selection of the cell it produces occurs. The B cells mature in the periphery and can recognize antigens in the secondary Iymphoid organs, proliferate and differentiate into the antibody secreting plasma cells. There are several populations of mature B cells that respond differently to the antigens. Splenic marginal zone B1 cells and B cells (MZ B cells) respond in an thymus independent antibody way, producing IgM. The follicular B cells (Fa B cells) produce antibodies in a thymus-dependent antibody way with changed isotypes and having high affinity for the antigen. They differentiate in long-lived plasma cells and memory B cells that maintain our humoral immunity.