FIG. 1.

HTSU-IgG binds to various cell types. (A) Binding of HTSU-IgG to primary CD4⁺ T cells and two T-cell lines. Primary CD4⁺ T cells were isolated and activated by PHA and IL-2 as described in Materials and Methods and assayed 4 days after the addition of IL-2. Primary CD4⁺ T cells, MOLT-4 cells, and Jurkat cells were incubated with 100 ηg of HTSU-IgG (shaded)/ml or, as a negative control, 500 ηg of SUA-rIgG (unshaded)/ml. The cells were then incubated with a FITC-conjugated antibody specific for rabbit IgG, and the amount of binding was determined by flow cytometry. (B) Binding of HTSU-IgG to non-T-cell primate cell lines. Binding assays were performed on 293, HeLa, and B5 cells as described for panel A.