Paired Epstein-Barr virus (EBV)-negative and EBV-converted Burkitt lymphoma lines: stimulatory capacity in allogeneic mixed lymphocyte cultures

Epstein-Barr virus (EBV)-negative Burkitt lymphoma lines (BLE-) and their in vitro EBV-converted sublines (BLEc), obtained by infection with the P3HRI and B95-8 strains of EBV, were compared for their capacity to induce T-lymphocyte proliferation in allogeneic mixed lymphocyte cultures (MLC). Regardless of the virus strain used for conversion, the BLEc lines induced a considerably stronger primary MLC response than their EBV-negative parentals. Only the BLEc lines were able to maintain T-lymphocyte proliferation in repeated stimulations. The low proliferative response observed in cultures stimulated with BLE- cells was not due to the generation of suppressor cells or to the release of inhibitory factors. The increased stimulatory capacity of BLEc lines was unrelated to changes in expression of MHC class-I and class-II antigen, or of B-cell activation markers, and was not due to the reactivation of EBV-specific memory T cells, since lymphocytes from EBV-seropositive and seronegative donors responded similarly. The results indicate that the capacity of BL cells to elicit cellular immune responses may be influenced by their EBV-carrying status.