Detection of infectious immune complexes in human immunodeficiency virus type 1 (HIV-1) infections: correlation with plasma viremia and CD4 cell counts.

The detection of infectious immune complexes in plasma after human immunodeficiency virus (HIV) infection may be useful as a surrogate marker of progression of disease and may help in understanding the pathogenesis of AIDS. Polyethylene glycol (PEG) precipitates of plasma were tested for the presence of HIV p24 antigen and infectious virus. Results were compared with data from cell and plasma cultures, plasma p24 antigen, CD4 cell counts, and stage of disease. PEG precipitation increased the detection rate of the p24 antigen assay from 38.3% to 58.7%. There was a significant correlation between precipitable p24 antigen and plasma viremia, changes in CD4 cell counts, and progression of disease. The sensitivity of the PEG-precipitable p24 antigen assay versus traditional p24 antigen testing was 59.0% and the specificity 91.7%. The assay was reproducible and may be a useful determinant of viral load, clinical progression, and antiretroviral efficacy.