CDR3-independent expansion of Vδ1 T lymphocytes in acquired chronic pure red cell aplasia.

Although there exist case reports describing the association of clonal expansion of γδ T cells with chronic acquired pure red cell aplasia (PRCA), there is no consensus regarding whether clonal expansion of γδ T cells are generally found in chronic PRCA. We examined the γδ T cell receptor repertoire in 19 PRCA patients and found that there was a difference in γδ T-cell repertoires between PRCA patients and healthy donors. We observed an increase in Vδ1 γδ T cells and a decrease in Vδ2 T cells in PRCA patients. CDR3δ1 size distribution patterns were skewed in 9 out of 13 PRCA patients examined, although the skewing was also observed in 7 out of 10 healthy individuals. No significant changes were present in CDR3δ1 size distribution between PRCA patients and healthy donors. Moreover, no apparent consensus amino acid motifs were identified in PRCA patients. Expansion of Vδ1 T cells and depletion of Vδ2 T cells are unique features for chronic acquired PRCA but expansion of Vδ1 T cells does not seem to be the consequence of CDR3-dependent selection. We conclude that clonal expansion of Vδ1 T cells is not a general feature for chronic acquired PRCA.