Immunological resistance is defined as either central or peripheral, depending on whether it is caused in the thymus and bone marrow (central) or other tissues and lymph nodes (peripheral) (peripheral). These types of tolerance are developed by different mechanisms, but the end result is the same. The ability of immature B cells in the bone marrow to recognise antigens is crucial for the production of immunological tolerance to self. This results in a population of B cells that do not recognise selfantigens but can recognise pathogen or non-self antigens. T cells are subjected to much more stringent survival selection than B cells. To generate T cells that recognise self-MHC molecules but not self-peptides, they are subjected to both positive and negative selection. Since central tolerance isn't 100 percent effective, peripheral T-cell tolerance mechanisms are needed to prevent autoimmunity. Numerous forms of regulatory T cells maintain active peripheral tolerance, the most well-known of which are FoxP3+ Tregs, which form naturally in the thymus or can be induced in the periphery.
Published Date: 2021-09-30; Received Date: 2021-05-11