Inducement of specific CTLs by antigen-peptides from human leukemia cells and their cytotoxicity to leukemia cells.

To investigate the inducement of cytotoxic T lymphocytes (CTLs) by antigen peptides mixture from different leukemia cells and the cross-reaction of the mixtures from different cell lines, antigen peptides mixtures were prepared from different leukemia cell lines respectively and then bound with Hsp70 in vitro. Activation and proliferation of PBMC were observed after stimulation with different Hsp70-peptide complexes. The ratio of CD8+ in proliferative cells was analyzed by flow cytometry. The cytotoxicity of the activated PBMC to different target cells was assayed. The results showed that the antigen peptides from different leukemia cell lines, bound with Hsp70, could activate PBMC effectively, and stimulate the activated PBMC to proliferate. The proliferative PBMC had specific cytotoxicity to corresponding leukemia cells. CD8+ cells, accounting for a high proportion in proliferative cells, had a specific cytotoxicity to leukemia cells from which antigen peptides were prepared, suggesting that these CD8+ cells were CTLs specific to leukemia cells. CTLs activated by Hut78-peptides or Molt4-peptides had a significantly stronger cytotoxicity to Hut78 cells, Molt-1 cells and Jurkat cells than that of CTLs activated by HL-60-peptides (P < 0.05). And the cytotoxicity of CTLs activated by Hut78/Molt4-peptides to Jurkat cells was significantly stronger than that of CTLs activated by either Hut78-peptides or Molt4-peptides alone (P < 0.05). It is concluded that antigen peptides mixtures from leukemia cells can induce specific antitumor CTLs. There exists cross-reactivity among antigen peptides mixtures from different cell lines of the same type leukemia and more cross-reactive antigen peptides could be obtained from more cell lines, suggesting that antigen peptides mixture with broad antigenic spectrum could be prepared by using multiple leukemia cell lines.