Assessing diversity: immune reconstitution and T-cell receptor BV spectratype analysis following stem cell transplantation.

T-cell receptor (TCR) BV spectratyping provides information concerning immune reconstitution complementary to that derived from monoclonal antibody analysis of surface antigen expression. However, the most appropriate way to analyse and represent these data, the number of subfamilies that should be analysed, and the effects of CD4/8 ratio on observed diversity, remain unclear. A diversity scoring system was developed based on analysis of 11 cord blood (CB) and 12 normal adult BV spectratypes. CB subfamily spectratypes demonstrated minor deviations from a Gaussian pattern consistent with current knowledge about germline TCR rearrangements. Diversity scores were significantly lower in myeloma patients than normal adults (P < 0.001) and fell significantly following stem cell transplantation (P = 0.003). Subsequently increasing diversity was not detected by two previously described complexity scoring systems. The CD4/8 ratio was neither the major determinant of the absolute diversity score nor of the change in score for individual patients, suggesting that analysis of unselected mononuclear cells can provide information largely independent of CD4/8 ratios. There was a relatively low correlation between individual subfamily scores and overall diversity score. The novel and objective diversity scoring system described appears better able to document changes in spectratype patterns than previously described techniques and should aid the standardization of reporting.