In the nasal epithelial cells of HIV-negative patients who suffered from respiratory infections beta-defensin levels were decreased. beta-defensin 1 mRNA expression was significantly reduced in alveolar macrophages from HIV infected patients. beta-defensin 2 mRNA expression in alveolar macrophages was very low. beta-defensins 1 and 2 mRNA expression did not correlate with CD 4 cell numbers in the blood of HIV-infected patients.