Peripheral blood mononuclear cells from house dust mite allergic patients produce IL-2 in response to specific allergen challenge

Proliferative responses and production of IL-2 by peripheral blood mononuclear cells of patients with Dermatophagoides pteronyssinus rhinitis +/- asthma were measured at up to 24 hr intervals from 1-8 days, after stimulation with mitogen (PHA), antigen (SKSD) and specific allergen (D. pteronyssinus). IL-2 was measured in culture supernatants using the murine CTLL cell line bioassay. Compared to non-atopic controls, patients had significantly higher proliferative responses to D. pteronyssinus and SKSD but similar responses to PHA. In patients, maximal proliferative responses to PHA, SKSD and D. pteronyssinus were at 3, 6 and 7 days, respectively. IL-2 levels in response to stimulation with D. pteronyssinus were significantly higher in patients than controls, where only background levels were found (15.4, 7.9-30.7 x 10(-2) U/ml [mean, range] n = 11; vs 2.2, 0.1-8.4 x 10(-2) U/ml, n = 6; P < 0.05). In contrast, IL-2 production to PHA and SKSD, although higher in patients, was not significantly different than controls. These results suggest allergic patients possess a population of T cells expandable by specific allergen which are induced to secrete IL-2.