FIG. 4.

Stimulation of the 4E6 T-cell hybridoma with V8 protease fragments of the 62-kDa antigen. (A) Stimulation of T-cell hybridoma 4E6 by, from left to right, the intact 62-kDa antigen, the fragments of the 62-kDa antigen derived from digestion with 2 μg of V8 protease, and the most stimulatory fragment g. Each of these stimulatory activities was obtained from an initial 450 μg of SEA. Data are expressed as mean ± 1 SD. Background radioactivity from hybridoma cultures in the absence of antigen is subtracted. (B) Corresponding silver-stained SDS-PAGE profile of, from left to right, the 62-kDa antigen, the combined V8 protease fragments of the 62-kDa antigen, and fragment g. Five percent of each antigen preparation used for stimulation was examined on the SDS-polyacrylamide gel. Part of the V8 protease migrated close to fragment g but had no stimulatory activity (not shown). The position of intact V8 protease (28 kDa) is shown.