ANALYSIS OF DENDRITIC-CELL-INDUCED PRIMARY T-CELL RESPONSES BETWEEN HLA GENOTYPICALLY IDENTICAL INDIVIDUALS

DCs are known for their superior antigen-processing and antigen-presen ting capacities. They are capable of processing intact protein: either endocytosed exogenous proteins or newly synthesized endogenous viral and bacterial proteins. They are potent inducers of primary T-cell imm une responses such as in allogeneic MLRs. It is also known that DCs ca n provide a strong stimulus for autologous T-cell proliferation. So fa r no information exists on the capacity of DCs to induce primary mH an tigen-specific T-cell responses. Therefore, we investigated whether hu man DCs, isolated from peripheral blood, were able to generate specifi c T-cell responses between MLR-negative HLA genotypically identical in dividuals in vitro. To this end, unfractionated cells, monocytes, and B cells were assayed in parallel with DCs to compare their capacity to activate unprimed T cells in a primary MLR. DCs indeed induced signif icant proliferation between HLA genotypically identical siblings, wher eas the other APCs were unable to evoke any T-cell response at all. As expected, besides these allogeneic T-cell responses, autologous T-cel l responses were initiated by the DCs as well. Nonetheless, despite fu rther detailed analyses of the responding T cells, neither proliferati ve nor cytotoxic mH antigen-specific reactivities could yet be detecte d using the stimulation protocols described herein.