<prompt> Lack of reaction to our own HLA human leukocyte antigen is known as?AutoimmunityClonal selectionToleranceComplement system  <response>: Immunologic tolerance is the phenomenon of unresponsiveness to an antigen-induced by exposure of lymphocytes to that antigen. Self-tolerance refers to lack of responsiveness to an individuals own antigens, and it underlies our ability to live in harmony with our cells and tissues. The mechanisms of self-tolerance can be broadly classified into two groups: central tolerance and peripheral tolerance Central Tolerance: In this process, immature self-reactive T and B lymphocyte clones that recognize self-antigens during their maturation in the central or generative lymphoid organs the thymus for T cells and the bone marrow for B cells are killed or rendered harmless. Several mechanisms silence potentially autoreactive T and B cells in peripheral tissues Anergy: Lymphocytes that recognize self-antigens may be rendered functionally unresponsive, a phenomenon called anergy. Suppression by regulatory T cells: A population of T cells called regulatory T cells functions to prevent immune reactions against self-antigens. Deletion by apoptosis. T cells that recognize self-antigens may receive signals that promote their death by apoptosis.. Robbins pathology 9e pg:214 