Responses of CD4⁺ T lymphocytes from CMV-seropositive healthy adults to CMV lysate. (A) Flow cytometry histograms, gated on CD3⁺CD4⁺ lymphocytes, showing intracellular IFN-γ production by the TIA-1⁺ subset in response to CMV lysate. (B) Flow cytometry histograms, gated on TIA-1⁺ CD3⁺CD4⁺ lymphocytes, showing expression of CD69 and CD25 after incubation of whole blood for 48 hours with CMV lysate. (C) Flow cytometry histograms, gated on CD3⁺CD4⁺ lymphocytes, showing proliferation of TIA-1⁺ cells in response to CMV lysate. Results are representative of 3 to 4 experiments.