DETECTION OF RECTAL ANTIBODIES TO HIV-1 BY A SENSITIVE CHEMILUMINESCENT WESTERN-BLOT IMMUNODETECTION METHOD

Western blot with a time-dependent enhanced chemiluminescence immunode tection method (ECL-WB) was shown to be 100-fold more sensitive than s tandard commercial colorimetric Western blots (WB) for detecting serum IBG to human immunodeficiency virus type 1 (HIV-1). ECL-WB was then u sed to test rectal secretions from 15 HIV-1 infected subjects (HIV +) and 7 uninfected subjects (HIV -) to document local IgG, IgA, and secr etory component-associated immunoglobulin (SC-Ig) to HIV-1 proteins. F ourteen of 15 HIV + subjects had rectal IgA to at least 1 HIV-1 protei n, most often to gp41 (80%) or p24 (60%) and 14 (93%) had IgG to gp160 , gp120, or gp41. Of seven HIV - subjects, none had detectable bands t o HIV-1 proteins. SC-Ig to HIV-1 proteins was detected in all five rec tal samples tested. However, the antibody profiles differed from those of rectal IgA, suggesting more than one source of rectal IgA to HIV. ECL-WB requires individual optimization and interpretation for each sp ecimen as well as expensive reagents and is, therefore, not currently applicable to screening assays. However, the method offers promise as a sensitive method to characterize low-level immune responses (IgG, Ig A, and SC-Ig) to HIV-1 proteins at local sites such as rectal mucosae.