MHC class I–negative allogeneic cell line induces tumor-specific CTLs as efficiently as its class I–positive counterpart.

Effector cells were obtained from popliteal lymph nodes after footpad immunization of BALB/c mice with allogeneic class I–negative (♦) or class I–positive B78H1 (■) cells, both of which share the TAA env-gp70 with C26 cells. After a 5-day restimulation in vitro with C26 cells (A-B,D) or with class I–positive B78H1 cells (C), lymphocytes were tested in a standard 4-hour ⁵¹Cr release assay. Target cells are C26 tumor cells (A), BALB/c-derived blasts previously pulsed (B) or not (D) with AH1 peptide, and C57BL/6-derived blasts (C). Data shown are representative of 3 independent experiments with similar results.