FIG. 1.

Binding of HIV IC to tonsil B lymphocytes. Tonsil B cells (2 × 10⁶) were incubated for 2 h at 4°C with HIV IC, which were prepared by incubating HIV PI (6,000 pg of p24) from three different subjects (PI 1 [A], PI 2 [B], and PI 3 [C]) with heat-inactivated (56°C for 45 min) autologous patient plasma (final dilution, 1:30) as a source of antibody (Ab) and with normal human serum from a seronegative AB⁺ donor as a source of complement (C) or HIC (final dilution, 1:10) for 50 min at 37°C (final incubation volume of 200 μl). Cells were washed and then lysed with 0.5% Triton X-100, and the amount of cell-bound virus was determined by a p24 ELISA (AIDS Vaccine Program, National Institutes of Health, Frederick, Md.). Each bar represents the mean ± the standard error of the mean of results from three experiments. HIV-1 PI were obtained by coculturing 2 × 10⁶ PBMC from HIV-infected donors at a 1:1 ratio with PBMC from an uninfected donor that were prestimulated for 3 days with 3 μg of PHA (Sigma Chemical Co., St. Louis, Mo.) per ml and 25 U of interleukin-2 (Boehringer Mannheim, Indianapolis, Ind.) per ml (21). All three PI donors were asymptomatic. Tonsil mononuclear cells were separated by the teasing of tonsil tissue, followed by filtration through a 70-μm-pore-size nylon Spectra/Mesh filter (Spectrum Medical Industry, Inc., Houston, Tex.) before being washed with RPMI 1640 (Whittaker Bioproducts, Walkersville, Md.) culture medium containing 1% l-glutamine, 25 mm HEPES, 10% heat-inactivated fetal bovine serum (Whittaker Bioproducts), and gentamicin (Sigma). B cells were isolated by negative selection with a mixture of anti-CD8 and anti-CD4 magnetic Dynabeads (M-450) (Dynal, Oslo, Norway). The resultant B-cell-enriched preparations were >95% CD19⁺.