FIGURE 6.

Exogenous IL-2 is required for the acquisition of CLTp cytotoxic function, and pretreatment of CTLps with IL-2 abrogates inhibition of cytotoxic function on exposure to HSV-1–infected splenocytes (Spl) and HSV-1 infected corneal fibroblasts (cFb). Eight days after HSV-1 corneal infection, DLN suspensions enriched for CD8⁺ T cells by CD4 and MHC class II depletion were cultured for 48 hours with 1 × 10⁶ Spls and a monolayer cFbs. (A, B) Cultures received 10 U/mL rmIL-2, medium alone (No IL-2), or medium plus α-IL-2R mAb (No IL-2 + αIL-2R) for the duration of the culture. (A) Cells were removed from the cultures and exposed to ⁵¹Cr-loaded HSV-1–infected target cells. Cytotoxicity was measured in a 3.5-hour ⁵¹Cr release assay. Statistically significant differences (P < 0.05) were obtained between all three groups at both E:T ratios. Percentage of specific lysis from control cultures that received medium only plus an isotype control antibody was nearly identical with that of cultures that received medium only (not shown). (B) Before cytotoxicity assays, culture supernatants were tested for IFN-γ content by ELISA. (C, D) CTLps were pretreated with 10 U/mL IL-2 or medium only for 16 hours before restimulation with HSV-Spls and HSV-cFbs and were analyzed. Percentage of specific lysis against uninfected targets was less than 5% for all culture conditions at all E:T ratios. Data are presented as the mean ± SEM of triplicate samples and are representative of at least two independent experiments with nearly identical results.