Figure 2.

Binding of SEA, SEB, and TSST-1 on DR-expressing cells lines and purified non-T PBMCs from a DR1 homozygous individual. (A) Specific binding of ¹²⁵I-SEA, -SEB, or -TSST-1 with (+) or without (−) a 10-fold excess of cold competitor. (B) Binding of the toxins to class II-expressing peripheral mononuclear cells (5 × 10⁶) from a DR1 homozygous individual with (+) or without (−) a 10-fold excess of cold toxin. In all these experiments the binding was compared (using the same toxin preparation and comparable amounts) to DAP DR1 cells to confirm the functional integrity of the toxins (data not shown). Standard variations for each point (duplicates) is represented in the error bars.