The capacity of the cultured HPCs from TNF-Rp55^+/+ or TNF-Rp55^−/− mice bone marrow to stimulate allogenic MLR. Lin⁻c-kit⁺ HPCs were obtained from TNF-Rp55^+/+ or TNF-Rp55^−/− mice bone marrow cells and incubated for 14 days in the presence of the indicated combinations of cytokines. Allogenic MLR was performed using purified T cells and cultured HPC progenies as responder and stimulator cells, respectively, as described in the Materials and Methods.