A rapid method for quantitating lymphocyte receptor capping: capping defect in AIDS patients

Capping of concanavalin A (Con A) and anti-Leu-8 (L8) receptors on human peripheral blood mononuclear (PBM) membranes was studied utilizing fluorochromeconjugated ligands and flow cytometric analysis. Histogram profiles of fluorescent intensities consistently revealed a time-dependent decrease in numbers of brightly fluorescing events concurrent with an increase in numbers of dimly fluorescing events when capping occurs. Differences in fluorescence profiles were detectable by flow cytometric analysis as early as 5 min after capping conditions were initiated. A pronounced defect in receptor capping of PBM cells from AIDS patients was observed. This technique represents a rapid and reproducible means for detecting early changes in cell membrane receptor mobility.