Frequency of allospecific CTL precursors is affected by the culture time-span.

(A) MLR of PBLs (squares), standard 14-day cultured RV cells (triangles), and 28-day cultured RV cells (circles; RV 28) against fully mismatched PBMCs was performed. After 1 round of in vitro stimulation, effector cells were tested against the same allogeneic target (closed symbols) and autologous PHA-derived lymphocytes (open symbols) in a standard cytotoxicity assay, performed in cold inhibition. The frequency of CD8⁺ T-cell precursors elicited in PBLs (B), RV cells (C), and RV 28 cells (D) with 1 round of stimulation with fully mismatched PBMCs was measured by stimulating the effectors in limiting dilution numbers and by performing a cytotoxic assay. Regression curves were interpolated, and precursor frequencies were determined according to Poisson statistics. Precursor frequencies are shown.