Functional analysis of LCL-reactive CD4⁺ T-cell clones isolated from EBV-seropositive (P1) and EBV-seronegative (N1 and N3) donors. (A) T cells (10⁴ cells/well) were cocultured overnight with standard numbers (5 × 10⁴ cells/well) of autologous B95.8 and BZ k/o LCLs, CD40L-activated B lymphoblasts (B blasts), PHA-activated T lymphoblasts (T blasts), and dendritic cells (DCs) all grown in human serum. (B) Autologous LCLs were incubated for 1 hour in the presence of mAb to HLA class I (aHLA I), HLA-DP (aDP), HLA-DQ (aDQ), HLA-DR (aDR), or medium as a control (B95 LCL) before the addition of T cells to the assay. (C) T cells were cocultured overnight (as in panel A) with cells of the autologous B95.8 LCL (Auto) and of partially HLA class II–matched allogeneic LCLs (Allo LCLs), for which the matched allele is shown in each case. All results shown are the mean ± 1 SD of triplicate wells in which IFNγ release into the supernatant medium was determined by ELISA (in ng/mL). Results are representative of those seen on 3 occasions of testing and include only a subset of the total number of target LCLs tested.