ACTIVATED LYMPHOCYTES REDUCE ADHERENCE OF ASPERGILLUS-FUMIGATUS

Lymphocytes comprise up to 30% of the cells present in human bronchoal veolar lavage fluid and thus could participate in host response to inf ectious Aspergillus fumigatus conidia. We have examined the possibilit y that lymphocytes might play a role during early infection by either damaging the fungus or interfering with adherence. When incubated with A. fumigatus conidia for 20 h, highly purified 5-day-old lymphocytes activated with either IL-2 or phytohaemagglutinin, but not untreated l ymphocytes, were consistently able to reduce residual fungal biomass a s estimated by a metabolic assay. T lymphocytes, but not NK cells, app eared to be responsible for this activity. Lymphocytes bound both A. f umigatus conidia and hyphae, and the antifungal activity of the lympho cytes required direct lymphocyte-fungus contact. In a separate set of experiments using release of Cr-51 from Cr-51-loaded fungi as an estim ate of fungal damage, lymphocyte-induced loss of fungal biomass was fo und to be due to loss of fungal adherence rather than to direct fungal damage. The detached hyphae were also found to be metabolically intac t and to have normal morphology by electron microscopy. These data dem onstrate that IL-2- and phytohaemagglutinin-activated lymphocytes exhi bit a contact-dependent ability to reduce adherence of germinating con idia of A. fumigatus to a surface.