OBJECTIVETo explore polarization of T lymphocyte and its relationship with apoptosis of marrow cells in patients with myelodysplastic syndromes (MDS).

METHODSMeasurements of Th1, Th2, Tc1, Tc2 subsets in bone marrows from 34 patients with MDS and 13 normal controls were performed by flow cytometry. INF-gamma and TNF-alpha in marrow serum were determined by ELISA (Enzyme-linked immunosorbent assay). Apoptosis index of marrow cells was detected by TUNEL (TdT-mediated dUTP nick end labeling). Correlations between Th1, Th2, Tc1, Tc2 subsets and INF-gamma, TNF-alpha levels as well as apoptosis index were analyzed, and relationship between TNF-alpha, INF-gamma levels and apoptosis index was also investigated.

RESULTS(1) The percentage of Th1 cells [(10.1 +/- 1.6)%], Tc1 cells [(24.0 +/- 3.6)%] and Tc1/Tc2 ratio (50.0 +/- 11.1) was significantly increased in patients with MDS than in normal controls [(4.0 +/- 0.5)%, (5.8 +/- 0.6)% and 13.4 +/- 2.7, respectively]. Levels of INF-gamma [(58.6 +/- 21.7) microg/L] and TNF-alpha [(15.7 +/- 3.8) microg/L] in marrow serum of MDS patients was markedly elevated compared to normal controls [0 and (0.3 +/- 0.2) microg/L, respectively]. An increased apoptosis index of nucleated cells was observed in MDS patients [(7.8 +/- 1.5)%] as compared to controls [(2.1 +/- 0.3)%, P < 0.05]. The Th1 cell percentage showed a positive correlation with the levels of INF-gamma and TNF-alpha (r = 0.38, P < 0.05 and r = 0.39, P < 0.05, respectively), and with apoptotic index of nucleated marrow cells in MDS patients (r = 0.33, P < 0.05). Furthermore, a positive correlation was observed between INF-gamma, TNF-alpha levels and apoptotic index of marrow cells (r = 0.74, P < 0.01 and r = 0.73, P < 0.01, respectively). (2) Th1, Tc1 cells and Tc1/Tc2 ratio in MDS-RCMD patients was markedly elevated (P < 0.01) but did not in RCMD-RS, RAEB-1 and RAEB-2 patients as compared to normal controls. (3) An elevation in the percentages of Th1, Tcl and Tc1/ Tc2 ratio was detected in patients with IPSS lower-risk but did not in higher-risk group as compared to controls. (4) Increased Th1 and Tc1 percentages and Th1/Th2 and Tc1/Tc2 ratios were observed in RCMD patients with normal karyotype, but did not in those with abnormal karyotype. Conclusions Th1/Th2 and Tc1/Tc2 in bone marrow of MDS patients were unbalanced, polarizing to type I reaction especially in patients with RCMD subtype, IPSS lower-risk and normal karyotype. The increased Th1 cells in bone marrow may account for the increased apoptosis of nucleated marrow cells in MDS, through proapoptotic cytokines such as INF-gamma and TNF-alpha.