Th1/Th2 lymphocyte balance in patients with aplastic anemia.

Activated T cell plays an important role in the pathogenesis of aplastic anemia (AA). CD4+ T cells are divided into Th1 cells producing hematopoietic inhibitory cytokines like interferon-gamma and Th2 cells producing interleukin-4. We investigated the Th1/Th2 cell ratio in the peripheral blood of AA patients treated with immunosuppressive therapy (IST). There were 10 patients who responded well to IST (responders) and 3 patients who were refractory to IST (non-responders). Th1 cells were lower in responders than in non-responders (16.2+/-2.4% vs. 28.8+/-5.5%, respectively, p<0.05), whereas Th2 cells did not differ. The Th1/Th2 ratio was also significantly lower in responders than in non-responders, being 13.2+/-1.5 and 40.4+/-5.1 (p<0.001), respectively. In three responders, the Th1/Th2 ratio was declined according to the hematological recovery (from 10.6 to 8.3, 16.3 to 10.9 and 11.8 to 9.5). Our results suggest that Th1 lymphocytes are more predominant in AA, and it may be very useful to monitor the Th1/Th2 ratio during IST.