Figure 5. Sp1 induces TCR-mediated activation in CD8⁺CD28⁻ T lymphocytes.

A. Sp1 induces phosphorylation of Zap-70 kinase and total Zap-70 kinase in CD8⁺CD28⁻ T lymphocytes. CD8⁺, CD8⁺CD28⁻, and CD8⁺CD28⁺ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 4 h. Western blotting was performed with a phospho-Zap-70, Zap-70 kinase-, and a β-actin-specific antibody as a control. A representative blot out of three experiments is shown. B. Sp1 induces NF-κB activity in CD8⁺CD28⁻ T lymphocytes. CD8⁺, CD8⁺CD28⁻, and CD8⁺CD28⁺ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 2 h. The nuclear extract of treated cells from 4 mice was analyzed by ELISA for NF-kB activity. As a positive control, the nuclear extract from Jurkat cells and as a negative control complete lysis buffer was used. The experiment was repeated three times in an independent manner. Columns indicate the mean NF-kB activity, bars indicate the standard deviation. **p<0.001,*p = 0.01.