Abstract
Th2 dominancy in the peripheral T helper (Th) cell subsets were reported to be involved in the pathogenesis of pure red cell aplasia (PRCA). We encountered a PRCA case secondary to plasma cell dyscrasia that showed Th2 dominancy at the relapse of PRCA. Increased expression of c-maf, a transcriptional factor which induces Th2 differentiation of naive T-cells, and elevated expression of interleukin (IL)-4 were observed in the RNA derived from patient's bone marrow at relapse of PRCA. Following the administration of methylprednisolone which improved PRCA, normalization of Th1/Th2 ratio and decreased expression of c-maf and IL-4 were observed, which suggests that the upregulation of c-maf might have played a role in the pathogenesis of PRCA secondary to plasma cell dyscrasia.