Frequency of Th0, Th1, and Th2 cells in uninfected, bystander, and productively infected CD4⁺ T cells. CD4⁺ T cells were enriched and infected with HIV as described. Cells were stimulated with anti-CD3/CD28 for 24 hours prior to Brefeldin A treatment and staining for HIV p24 and IFN-γ plus IL-2 or with IFN-γ plus IL-4. (A,D) Mock-infected cells. (B,E) Bystander cells. (C,F) HIV productively infected cells. Data are representative of at least 3 donors.