Epstein Barr virus selective T cells in infectious mononucleosis are not restricted to HLA-A and B antigens.

The cytotoxic T cells activated in vivo during a primary response to Epstein Barr virus (EBV) kill allogeneic target cells, whether or not they share HLA-A, B or C specificities with the targets. Some HLA preference can be demonstrated by a higher level of lysis only when the target cells are autologous with the effectors. Cryopreserved lymphocytes from 12 HLA-typed donors with infectious mononucleosis (IM) were treated against a panel of 51Cr-labeled EBV-positive (+) and negative (−) lymphoblastoid cell line (LCL) targets. In order to avoid NK activity, the lymphocytes were depleted of Fc receptor-bearing cells, resulting in a 60 to 90% decrease in cytotoxicity against K562 and other EBV-, NK-sensitive targets. These effectors produced 2 to 25% more cytotoxicity than the unfractionated cells against the EBV+ targets. As further insurance against NK, most of the LCL employed as targets were newly established and, therefore, resistant to NK. Although there was some variation in the levels of killing against the allogeneic EBV+ targets, this did not correlate with sharing of HLA antigens: some targets that shared no specificities with the effectors were killed as well or better than those share HLA-A, B or C antigens. This was also true of Fc receptor-negative IM effector T cells selected by sedimentation of SRBC-binding cells. The lymphocytes from 8 of the 12 donors tested showed preferential killing of their autologous LCL targets. It may be that effectors from any 1 donor are heterologous with respect to specificity: some clones may be restricted, whereas others may not be restricted to HLA identical targets.