ASPERGILLUS-FUMIGATUS CONIDIA INDUCE A TH1-TYPE CYTOKINE RESPONSE

The response of human peripheral blood mononuclear cells (MNC) to Aspe rgillus fumigatus in vitro was evaluated, In studies of the proliferat ive response of MNC from 18 healthy donors to heat-killed A. fumigatus conidia, 15 displayed a significant response, with a stimulation inde x (SI) between 4 and 193, In contrast, all donors displayed a positive response to Candida albicans blastoconidia (SI ranged from 10 to 224) . Despite the variability in reactivity to A. fumigatus conidia, the r esponse of a particular individual was stable when retested over perio ds of 1-2 weeks, Supernatant from cocultures of A. fumigatus conidia w ith MNC contained increased levels of interferon-gamma, granulocyte-ma crophage colony-stimulating factor, tumor necrosis factor-alpha, and i nterleukin (IL)-2, compared with unstimulated cells, but not IL-10 or IL-4, In addition, A. fumigatus induced lymphocyte surface expression of adhesion/activation-associated molecules. These results suggest tha t lymphocytes may contribute to host defense against Aspergillus by ge nerating a Th1-type response.