ACTIVATED HUMAN T-CELLS BESTOW T-CELL ANTIGENS TO NON-T-CELLS BY INTERCELLULAR ANTIGEN TRANSFER

The mechanism of the appearance of T-cell antigens on B-cells, followi ng in vitro activation of peripheral blood lymphocytes, was analyzed u sing the following model: Purified T-cell suspensions were activated b y exposure to phytohemagglutinin (PHA) for 3 days, and then incubated for one hour in the presence of cells of either Raji or K562 cells. Th e expression of T-cell antigens on the cell lines was determined using immunofluorescent F(ab)2 fragments of monoclonal antibodies (mAbs). F ollowing exposure of the CD19(+) Raji cells to activated T lymphocytes , 87.6% of the CD19(+) cells co-expressed CD2. A large proportion of t he CD19(+) cells also expressed CD4, CD5, and CD8 antigens. Similar re sults were obtained with Raji cells that were prelabeled with calcein AM. In Raji cells, which were rendered CD5(+) following incubation wit h activated T cells, only a negligible level of CD5 mRNA was detected with a sensitive RT-PCR technique, probably attributable to contaminat ion with T cells. K562 cells incubated with activated T cells acquired CD2 but not the CD4 and CD8 antigens. Exposure of either Raji or K562 cells to mAb against CD58 inhibited the transfer of CD2. The present study indicates that following their activation, T-cells gain the capa city to transfer T-cell antigens to non-T cells and that CD2 and CD58 molecules are involved in this process. (C) American Society for Histo compatibility and Immunogenetics, 1998. Published by Elsevier Science Inc.