Atopy as a minimal immunodeficiency?

Despite impressive recent advances in the understanding of the chemical and cellular bases of the reaginic response, the pathogenesis of atopic diseases still remains a matter of speculation. The frequent finding of atopic diseases in some primary immunodeficiencies such as selective IgA deficiency and the Wiskott-Aldrich syndrome offers a unique opportunity for studying the immune mechanisms underlying the genesis of atopy. Recent studies in subjects with selective IgA deficiency have challenged the well known hypothesis that atopy is the result of defective "immune exclusion" by the secretory immune system. A number of immunological features found in the primary immunodeficiencies associated with atopic disorders suggest that defective homeostatic mechanisms regulating reaginic responses may play a major role in the pathogenesis of atopy. A thorough analysis of these disease combinations may help to generate new working hypotheses concerning the immune pathogenesis of atopic diseases.