FIG. 8.

Pretreatment with rLTB preferentially depletes CD8⁺ responder T cells from MLR/CML cultures. (A) Responder spleen cells (R) from C57BL/6 (H-2^b) mice were pretreated (10⁷/ml) with 0.1, 1.0, or 10 μg of rLTB per ml for 1 h at 37°C (open bars) or with no rLTB (solid bar), washed, recounted, checked for viability, and then stimulated with mitomycin C-treated MHC-mismatched B10.BR (H-2^k) spleen cells (Sm) in MLR cultures for 5 days (see Materials and Methods). Cell proliferation was measured by pulsing with [³H]TdR for the final 6 h of culture. Mean counts per minute and standard deviations for triplicate samples are shown. (B) Effector CTL generated in the MLR culture were mixed with ⁵¹Cr-labeled target cells at various effector/target cell ratios in a 3.5-h CML assay (see Materials and Methods). The number of LU₃₀ per million effector cells was calculated for each culture. (C) Responding CD4 and CD8 T cells in the MLR cultures were quantified by SCDA assays as described in Materials and Methods. The data shown are average numbers of CD4⁺ (open bars) and CD8⁺ (solid bars) T cells per well on day 5 (means for duplicate samples). The value above each bar shows the ratio of CD4 to CD8 T cells.