Histamine and Basophils in Delayed-Type Hypersensitivity Reactions

Abstract

Abstract It has been known for some years that delayed-type hypersensitivity reactions in several species contain increased concentrations of histamine but the cellular localization of this amine is unknown. Recent studies have revealed that cellular hypersensitivity itself is not a homogeneous entity and that several forms of delayed-onset, lymphocyte-mediated hypersensitivity in animals and man are characterized by substantial infiltrations of basophilic leukocytes. These basophil-rich reactions to several protein, viral and tissue antigens and to contact allergens have been designated cutaneous basophil hypersensitivity (CBH) to distinguish them from true delayed hypersensitivity (DH) in which basophils are relatively infrequent. The possibility that basophils might account for the increased histamine in cell-mediated reactions was therefore considered. DH reactions to several protein antigens contained increased concentrations of histamine and a modest infiltration of basophils at 24 to 72 hr after skin test. CBH reactions to the same and other antigens including a contact allergen contained much higher concentrations of histamine and numerous basophils. In combined data obtained from CBH and DH reactions and from freeze-injured skin, a correlation coefficient of 0.62 ± 0.09 was found between the percentage of infiltrating basophils and the ratio of histamine concentration in experimental as compared with control skin. These data are consistent with the hypothesis that basophils account for the elevated histamine observed in cellular hypersensitivity reactions but do not exclude a lesser contribution by mast cells or possibly by other infiltrating or fixed tissue cells.