[In vitro cytotoxic effects of CML28 specific T cells on acute leukemia cells]

To explore the activation and proliferation of specific T cells induced by artificial antigen-presenting cells (aAPCs) simulated dendritic cells (DCs) and to observed the effect of these T cells on leukemic cell killing.

aAPCs were developed by coating a human leukocyte antigen-immunoglobulin fusion protein ( HLA-lg), which was connected each one of the four CML28 antigen epitopes (DLMSSTKGL, DLMSSTKGL, ALFCGVACA, VLTFALDSV), and CD28-specific antibody, to magnet-beads CML cell specific peptides (CML28) served as target peptides. Bone marrow (BM) or peripheral blood (PB) mononuclear cells (MNCs) were isolated from HLA-A2 healthy volunteers, and co-cultured with aAPCs. Specific T lymphocyte were detected by flow cytometry. The fresh acute leukemic cells were used as target cells. The specific T cells incubated with leukemic cells for 4 h at ratios of 5:1, 10:1, 20:1, 40:1, 80: 1, respectively. The effect of leukemic cells killing was detected by lactate dehydrogenase release test.

The average ratio of CML-28 specific T lymphocyte in control group was (2.2 +/- 0.4)% and in experimental groups (DLMSSTKGL, DLMSSTKGL, ALFCGVACA, VLTFALDSV) were (13.5 +/- 1.6)%, (15.2 +/- 1.5)%, (14.7 +/- 1.8)% and (34.3 +/- 3.5)%, respectively, being significantly higher than that in control group (P < 0.01). Induction efficiencies of acute leukemic cells killing were significantly enhanced by increase of effector cells. The cytotoxic activity of specific T lymphocyte in one experimental group (VLTFALDSV) was much higher than that in other three experimental group (P < 0.05).

This "prime and expand" regimen should be an alternative method for large scale amplification of rare tumor-specific CTLs and aAPCs might be a useful tool for leukemia immunotherapy.