Altered spontaneous and histamine-induced in vitro suppressor-cell function in dogs with atopic dermatitis.

Spontaneous, histamine-induced and Concanavalin A (Con A)-induced suppression of Con A mitogenesis of autologous responder cells was studied in normal dogs and in dogs with atopic dermatitis. Histamine-induced suppression was significantly decreased in the atopic dogs, as was the Con A-induced suppression, at supraoptimal concentration of Con A, to a lesser extent. Total numbers of histamine type 1 or type 2 receptors were not different for cells from atopic or normal dogs. The spontaneous suppression was significantly greater for the atopic dogs and this was not accounted for by the effect of non-specific dermatitis, increased macrophage-induced suppression or increased induction by mitogenic factors in the culture medium. Some possible mechanisms for these results are discussed, and the similarities to suppressor cell function in humans with atopic disease are noted.