FIGURE 1.

Egr-1 is expressed rapidly upon T cell activation and is expressed preferentially in Th2 cells. A, Egr-1 is induced rapidly upon T cell stimulation. Jurkat T cells were stimulated with either α-CD3/α-CD28 or PMA/ionomycin for the indicated times. Cell lysates were subjected to Western blot analysis with antibodies against Egr-1, Egr-2, and Egr-3. B–D, Egr-1 is expressed preferentially in Th2 cells. B, murine Th1 clone Cl29 and Th2 clone D10G4.1 cells were stimulated with PMA alone (P) or PMA plus ionomycin (PI) for 2 h. Nuclear extracts were analyzed by Western blotting for Egr-1 expression. Jurkat T cells were used as a positive control. The constitutive transcription factor YY-1 was used for control of equal loading. C, murine Th1 clone B10BI and L1/1 cells were stimulated with PMA or ionomycin alone or in combination for 2 h. Cell lysates were subjected to Western blot analysis. D, naïve CD4⁺ T cells (Th0) were differentiated under either Th1 or Th2 culture conditions. The differentiated cells were restimulated with α-CD3 for the indicated times. The cytokine expression profiles of differentiated cells were analyzed in supernatants by enzyme-linked immunosorbent assay. Total cell lysates were analyzed for Egr-1 expression by Western blotting. Tubulin was used to control equal loading. All results are representative of at least two independent experiments.