OBJECTIVETo investigate the expression of T cell early activation marker (CD(69)) on peripheral CD(4)(+) and CD(8)(+) lymphocytes and serum levels of soluble tumor necrosis factor receptor 1 and 2 (sTNF-R1 and sTNF-R2) in serum and bone marrow in patients with aplastic anemia (AA) and their pathophysiological significance.

METHODSIn vitro activation of T lymphocytes was carried out by whole blood cell culture containing PHA (20 micro g/ml). The CD(69) expressions on CD(4)(+) and CD(8)(+) lymphocytes at 0 h and 4 h after PHA exposure were analyzed by two-color flow cytometry. The levels of sTNF-R1 and sTNF-R2 in serum and bone marrow were measured by ELISA.

RESULTSThe CD(69) expression rates of CD(4)(+) and of CD(8)(+) cells in SAA patients were (8.96 +/- 7.23)% and (10.67 +/- 7.58)%, respectively, and that of CD(8)(+) cells in CAA patients was (7.36 +/- 5.49)% before PHA stimulation. The CD(69) expression rates of CD(4)(+) and of CD(8)(+) cells in SAA patients were (71.73 +/- 11.91)% and (61.74 +/- 13.44)% and in CAA (59.35 +/- 10.15)% and (48.78 +/- 8.25)% respectively, and were significantly elevated after PHA stimulation. CD(69) expression on CD(4)(+) cells was much higher than that on CD(8)(+) cells after stimulation. The levels of the two sTNF-R (sTNF-R1 and sTNF-R2) in peripheral blood and bone marrow of SAA patients were elevated and in the bone marrow of CAA patients were also increased. The serum levels of sTNF-R2 were positively related to the CD(69) expression rates of CD(8)(+) cells before PHA stimulation.

CONCLUSIONIncreased early activation and activated potentials of T lymphocytes, along with abnormally elevated immunologically active molecules might play a major role in the pathogenesis of AA.