Self-recognition is the consequence of a selection process that occurs in the thymus at a young age, for T-Cells, and in the bone marrow for B-cells. https://

Self-recognition is the consequence of a selection process that occurs in the thymus at a young age, for T-Cells, and in the bone marrow for B-cells. https://en.wikipedia.org/wiki/Thymus https://en.wikipedia.org/wiki/Thymus First, T cells undergo "Positive Selection" whereby the cell comes in contact with self-MHC expressed by thymic epithelial cells; those with no interaction are destroyed. Second, the T cell undergoes "Negative Selection" by interacting with thymic dendritic cell whereby T cells with high affinity interaction are eliminated through apoptosis (to avoid autoimmunity), and those with intermediate affinity survive. See also https://en.wikipedia.org/wiki/V%28D%29J_recombination https://en.wikipedia.org/wiki/V%28D%29J_recombination V(D)J recombination, also known as somatic recombination, is a mechanism of genetic recombination in the early stages of immunoglobulin (Ig) and T cell receptors (TCR) production of the immune system. V(D)J recombination takes place in the primary lymphoid tissue (the bone marrow for B cells, and Thymus for T cells). V(D)J recombination nearly randomly combines Variable, Diverse, and Joining gene segments in vertebrate lymphocytes, and because of its randomness in choosing different genes, is able to diversely encode proteins to match antigens from bacteria, viruses, parasites, dysfunctional cells such as tumor cells, and pollens.