Id-specific T-cell responses induced by Id-CTLA4 immunization.

C3H/HeN mice were immunized twice intraperitoneally with 10 μg Id or Id-CTLA4. Mice receiving PBS only served as controls. Splenocytes pooled from 3 immunized mice were stimulated with 50 μg 38C13 Id (■) or transferrin (▪). Values are presented as mean stimulation index for triplicate wells ± SD. The mean counts per minute for the mitogenic control (5 μg/mL concanavaline A) of the PBS, Id, and Id-CTLA4 groups were 32 305 ± 4196, 25 088 ± 3123, and 51 125 ± 4307, respectively. The mean counts per minute for the negative control wells (receiving cells only) of the PBS, Id, and Id-CTLA4 groups were 2151 ± 372, 1105 ± 168, and 1922 ± 274, respectively.