Envelope glycoprotein gp120 induces MAPK activation in TCR-engaged, but not IL-7–prestimulated, primary CD4⁺ T cells.

(A) CD4⁺ lymphocytes were prestimulated with either recombinant IL-7 (10 ng/mL) for 4 days or with immobilized αCD3 and αCD28 mAbs for 2 days, followed by a 2-day culture in the presence of recombinant IL-2. CXCR4 and CD4 expression were assessed at day 4 using PE-conjugated mAbs, and the respective histograms are indicated. Expression of the IL-2Rα (CD25) activation marker in these IL-7– and CD3/CD28-stimulated T cells was monitored, and the corresponding histograms are shown. (B) After 4 days of culture, cells were either restimulated with gp120, SDF-1, an αCD3 mAb, or an αCD4 mAb, as indicated. Membranes immunoblotted with a pAb recognizing the dually phosphorylated Erk1/Erk2 are shown. Blots were reprobed with an αZAP-70 mAb to assess expression of a T-cell–specific protein in these differentially stimulated T cells. Results are representative of data obtained in 1 of 3 independent experiments.