Decreased production of local immunoglobulin a to Pneumocystis carinii in bronchoalveolar lavage fluid from human immunodeficiency virus-positive patients

An enzyme-linked immunosorbent assay and a Western blot analysis were devel oped to study the antibody response to Pneumocystis carinii in serum and br onchoalveolar lavage fluid from 27 human immunodeficiency virus 27 (HIV)-in fected patients with P. carinii pneumonia (Pcp), 32 patients without Pcp, a nd 51 HIV-negative controls. Urea was used for the correct dilution of epit helial lining fluid, and albumin was used to evaluate transudation from pla sma for the assessment of local production of antibodies to P. carinii. By contrast with those of immunoglobulin G (IgG), IgA responses to P, carinii were increased in serum from HIV-positive patients compared to negative con trols. Local production of antibodies to P, carinii, especially IgA, was de creased in patients with Pcp, In a study of 10 patients of each group, IgG and IgA responses to gp116 from P. carinii were lower in patients with Pcp than in other groups. These results suggest that, in addition to alveolar m acrophages, local antibodies may play a role in host defense against P. car inii.