Effect of Excess of Antigen on the Active Anaphylactic Reaction in vitro

Abstract

THE similarities between the effects of the classic anaphylactic reactions and the reactions induced by antigen–antibody complexes suggest that there may be a similarity in the mechanisms responsible for these reactions. It is known that the ability of soluble complexes to produce anaphylactic reactions is governed by the quantitative relationship between antigen and antibody: the complexes prepared in slight-to-moderate excess antigen are most effective in producing anaphylactic reactions, whereas in greater than moderate antigen excess this effectiveness decreases with an increase in the amount of antigen added^1–3. Recently, it has been shown that the passive anaphylactic reaction is inhibited by very large excesses of antigen^4,5. In the present investigation on the release of histamine from actively sensitized peritoneal mast cells of the rat, it is shown that increasing excesses of antigen decrease the intensity of the anaphylactic reaction.