AF elevates the threshold number of TCRs required for IL-2 secretion.

Either Jurkat cells or T cells were stimulated with various concentrations of PHA or solid-phase OKT3 in the absence (▪) or presence of AF (○). (A) Percentage of TCR down-modulation in Jurkat cells as a function of PHA concentration, as measured by CD3 immunofluorescence and flow cytometry. (B) Percentage of TCR down-modulation in T cells as a function of OKT3 concentrations. (C) IL-2 secretion by Jurkat cells as a function of the percentage of TCR down-modulation, as calculated from the data in Figure 1, panel A, and panel A herein. The data represent the mean of triplicate samples. Comparable results were obtained in 3 separate experiments.