Influence of residential fungal contamination on peripheral blood lymphocyte populations in children

Reported residential fungal contamination has been associated consistently with increased symptoms among occupants; however, an objective measure of a health effect is lacking, and a pathophysiologic mechanism has not been established. Our objective was to determine if exposure to indoor fungal contamination influenced T-cell differentiation. In this study, we contrasted lymphocyte populations, measured by flow cytometry, between a group of children who lived in homes with considerable fungal contamination (n = 39) and a group in less-contaminated homes (n = 20). indicators of fungal biomass were viable fungi in house dust and air ergosterol in the child's bedroom. Living in a more-contaminated home versus a less-contaminated home was associated with a larger number of CD3(+) T cells expressing CD45RO (1.5 x 10(9)/l versus 1.1 x 10(9)/l, respectively; p = .05, two-tailed t testing) and a reduced CD4/CD8 ratio (1.6 versus 1.8, respectively; p = .04). The differences persisted over a 12-mo period, and they were not explained by the child's age or total serum IgE, dust mite antigens, and the presence of furry or feathered pets ora humidifier. The results suggest that residential fungal contamination leads to chronic stimulation of children's lymphocytes.