Proteins are essential elements of all living cells. A site on the surface of a cell which in a lock and key fashion fits into a complementary site on another cell or protein, as in the binding of an antibody to an antigen . Involving the entire system or body. Medications taken orally are systemic because they are distributed to the entire body. A type of lymphocyte involved in cell mediated immunity that matures under the influence of the thymus.
T cells destroy cells marked by antibodies or expressing specific antigens.
Suppressor T cells diminish the immune response, helping to regulate it. The concentration of a substance in solution as determined by titration. Antibody concentrations are measured this way. This tends to localize the treatment and minimize side effects.