Immediate Hypersensitivity: A Defense against Arthropods?

Abstract

IMMEDIATE HYPERSENSITIVITY: A DEFENSE AGAINST ARTHROPODS? JAMES H. STEBBINGS, JR.* It is known, but not widely recognized, that many reactions to insect bites are immediate hypersensitivity reactions [1, p. 146; 2]; that these reactions are far more common than hay fever, asthma, and other immediate hypersensitivity reactions of clinical importance is indisputable . I propose the hypothesis that a major function of the immediate hypersensitivity reactions has been the protection of terrestrial vertebrates from the bites of, or invasion by, arthropods. Beyond the obvious notion that the most common agent inducing a biological response may be a clue as to the function of that response, two observations induced me to pursue the line of thought presented in this paper. Since the time of Osier [3] hay fever has been considered a product of modern culture; Burnet has commented on its apparent increase in recent decades [4, p. 142]. A concurrent decrease in frequency of insect bites, and presumably of the immediate hypersensitivity reactions which often follow, has not been quantified but is scarcely deniable. Second, a frequent, readily observable, and presumably beneficial function of the immediate hypersensitivity reaction to insect bites in man is the inducement of avoidance behavior. The natural functions of reagirne antibodies, or immunoglobulin E, have remained obscure despite their clinical importance as mediators of atopic diseases [5; 6, p. 31]. Elevated serum IgE levels h…