Question

As far as I know, T and B cells form a part of the adaptive immune response in humans. In their early stages, these cells undergo genetic recombination to produce a diversity of antigen receptors/antibodies, before maturing in the thymus/bone. As a part of this maturation process, I understand that the body presents the lymphocytes the full set of molecules present in the body, and ones evoking an autoimmune response are eliminated. This maturation process allows lymphocytes to recognise the difference between pathogens and body cells/molecules. My question is this: Since the maturing lymphocytes are not exposed to pathogen-complementary antibodies before the primary response to a pathogen, does the body recognise the variable regions of these newly synthesized antibodies as foreign, generating a second wave of antibodies? This might cause the body to produce antibodies it doesn't need to, or unnecessarily remove useful antibodies from the blood by agglutination/phagocytosis.

Answer 1

The adaptive immune system, consisting of B cells and T cells, is selective in targeting pathogens and not the body’s own cells.

Step-by-step explanation:

The adaptive immune system is a highly specialized component of our body's defense mechanism. It primarily involves two types of lymphocytes: B cells and T cells. These cells are crucial in identifying and neutralizing pathogens such as bacteria and viruses. B cells, which mature in the bone marrow, are responsible for producing antibodies. T cells, maturing in the thymus, are vital for cell-mediated immunity which handles cells that are infected internally.

During their maturation process, both types of cells develop mechanisms to ensure that they do not target the body's own tissues. This is done through a selection process where cells that are reactive to self-antigens are eliminated, a concept known as central tolerance. Consequently, B cells that survive this process are equipped to produce antibodies that are specific to antigens from foreign pathogens, not self-antigens. These cells circulate in the body, in a primed but inactive state until they encounter their specific antigen.

Upon first exposure to a pathogen, B cells produce antibodies against it, initiating a primary immune response. Interestingly, the body does not recognize these newly synthesized antibodies as foreign because they are produced by its own cells and represent self-proteins. Thus, there is no secondary immune response against these antibodies. Instead, specific B cells develop into plasma cells and memory cells. Plasma cells actively secrete antibodies, whereas memory cells provide immunological memory for a more rapid response upon subsequent exposure to the same pathogen. The diversity of antibodies produced ensures that the immune system can respond to an immense variety of pathogens without mistakenly targeting the body’s own cells.