LOCAL ANTIBODIES AGAINST PNEUMOCYSTIS-CARINII IN BRONCHOALVEOLAR LAVAGE FLUID

Pneumocystis carinii pneumonia (PCP) is a frequent cause of pneumonia among human immunodeficiency virus (HIV)-infected patients. Little is known, however, about the role played by humoral immunity to control t he infection. This study was undertaken to elucidate the role played b y local antibodies. Bronchoalveolar lavage (BAL) fluids from 18 acquir ed immune deficiency syndrome (AIDS) patients with PCP, 20 HIV-antibod y positive patients without PCP, and 20 lung cancer patients were exam ined for antibodies against P. carinii by the indirect immunofluoresce nce method. The ratio of albumin concentration in BAL fluid to serum w as used to standardize the lavage fluids. Immunoglobulin G (IgG) antib odies against P. carinii occurred less frequently, and immunoglobulin M (IgM) antibodies more frequently, in PCP patients than in other grou ps. Immunoglobulin A (IgA) antibodies against pneumocysts were found w ith the same frequency in all three groups, although the median titre was lower among HIV-antibody positive patients without PCP, compared w ith the other groups. When indexed (antibody titre in BAL fluid x albu min concentration in serum/antibody titre in serum x albumin concentra tion in BAL fluid) to express locally produced antibodies, IgG indices were significantly higher in HIV-infected patients without PCP, where as IgM and IgA indices were significantly higher in PCP patients. Thes e findings suggest that the local IgG response is impaired in patients with PCP, whereas the local IgA and, to some extent, the IgM response s are preserved.