Brief report Distinct contributions of CD4 and CD8 naive and memory T-cell subsets to overall T-cell–receptor repertoire complexity following transplantation of T-cell–depleted CD34-selected hematopoietic progenitor cells from unrelated donors

Normalization of restricted T-cell–receptor (TCR) repertoire is critical following T-cell–depleted (TCD) stem cell transplantation. We present a prospective study analyzing respective contributions of naive and memory T-cell subsets within the CD4 and CD8 compartments to the evolution of overall TCR-repertoire complexity following transplantation of CD34selected peripheral blood progenitor cells from unrelated donors. During the first year after transplantation, sorted CD4/ 45RA, CD4/45R0, CD8/45RA, and CD8/ 45R0 subsets were analyzed at 3-month intervals for TCR-repertoire complexity by CDR3 size spectratyping. Skew in TCRrepertoire was observed only in early memory-type T cells. CD4 and CD8 subsets differed in clonal distribution of CDR3 sizes, with rapid Gaussian normalization of bands in CD4/45R0 T cells. Naive T cells displayed normal repertoire complexity and contributed significantly to skew correction. Our data provide direct evidence for an important role of de novo maturation of naive T cells in normalization of an initially restricted TCRrepertoire following transplantation of CD34-selected, TCD-depleted peripheral blood progenitors from unrelated donors. (Blood. 2002;100:1915-1918)