Modified wick method using Weck-Cel sponges for collection of human rectalsecretions and analysis of mucosal HIV antibody

Weck-Cel sponges were examined for suitability as an absorbent material for nontraumatic collection of rectal secretions in humans. Sponges were teste d in vitro and determined by quantitative enzyme-linked immunosorbent assay (ELISA) to be capable of releasing 100% of absorbed albumin and all immuno globulin subtypes after treatment with detergent-supplemented buffer. Prote in composition in rectal secretions collected from normal women with dry sp onges (DS) or with sponges previously softened by moistening with saline (M S) was subsequently compared. DS secretions showed evidence of contaminatio n with blood and interstitial fluid-derived albumin, immunoglobulin G (IgG) , and monomeric IgA. MS secretions appeared to represent local mucosal secr etions more accurately because they contained negligible blood, a greater p ercentage of secretory IgA within the total IgA, and both lower albumin/IgG ratios and more dramatic alterations in IgG subclass distribution compared with corresponding serum. Anti-HIV IgG, IgM, IgA, and antibodies with secr etory component could be demonstrated by ELISA in rectal secretions collect ed with moist sponges from 8 of 8, 1 of 8, 5 of 8, and 3 of 8 HIV-infected women, respectively. The data show that Weck-Cel sponges, if premoistened, can be used to collect rectal fluids nontraumatically and to obtain quantit ative information about concentrations of immunoglobulins and specific anti bodies on rectal mucosal surfaces.