Fig. 4.

Costimulation by CD81 preferentially activates signal transduction in naïve CD4 T cells. Isolated CD4 T cells were stimulated with 0.8 μg/mL of anti-CD3 together with 10 μg/mL of antibodies against the costimulatory molecules CD81 (5A6) or CD28. After permeabilization and fixation cells were stained for expression of CD4 and CD45RO and the phosphoproteins pPLCγ, pCD3ζ, pSLP76 and pS6. Shown is phosphorylation measured in resting cells (unstim) and after 8 min stimulation of the naïve (CD45RO low) and memory (CD45RO high) subsets. Data are representative of three independent experiments.