Adaptive immune responses are specific to a particular antigen. Provide and explain 3 examples which illustrate this concept

Question

What will be an ideal response?

Answer 1

1 ) Lymphocytes will recognize antigen using surface proteins called T cell receptors (TCRs) or B cell receptors (BCRs). Each lymphocyte is covered with many copies of these receptors, but each receptor on a given lymphocyte only recognizes one specific epitope of one specific antigen. 2 ) The body makes a diverse variety of TCRs and BCRs through a gene shuffling process as lymphocytes mature, so the body's capacity to respond to different antigens is nearly limitless. It is possible that during lymphocyte maturation, a cell with a receptor that responds to a molecule on normal body cells will be generated. To avoid an immune attack on normal cells, maturing lymphocytes are screened for self-tolerance. Those that attack normal cells are eliminated in this process. 3 ) Body cells are identified as "self" through a group of surface proteins called major histocompatibility complex (MHC) proteins. All body cells (except red blood cells) wear MHC 1 proteins, while immune cells which present antigen also wear MHC 2 proteins. When a cell is infected, altered such as by cancer, or has ingested an antigen for presentation, the foreign antigens will be displayed by the MHC proteins for recognition by T and/or B lymphocytes with receptors that recognize that antigen. To insure successful organ transplants, donor and recipient tissue must be matched so that their MHC proteins are as similar as possible. 4 ) During T cell activation, presentation of antigen by an antigen-presenting cells preferentially activates T cells whose receptors bind to that antigen. After activation, proliferation, and differentiation, all T cells clones will respond to the antigen that stimulated the original response. T cytotoxic cells will locate and eliminate cells displaying the specific antigen in question. 5 ) During a humoral response, a B cell with the correct receptor will bind to an antigen. After proliferation and differentiation of the B cell clones, the plasma B cells will secrete large quantities of antibody molecules who are able to specifically bind to the antigen which stimulated the B cell line.