BV⁺ CD4⁺ T cells are markedly depleted in CTCL. (A) The absolute number of BV⁺ CD4⁺ T cells was calculated by determining the percentage of BV⁺ CD4⁺ T cells by flow cytometry and obtaining absolute CD4 cell counts. The means ± SDs of stage III/IV (▪; n = 10, without the numerically expanded clones) and stage I/II (▦) CTCL patients (n = 7) are shown in comparison to normal values (□) for each BV subfamily. Normal values represent the average number of CD4⁺ T cells (1100/mm³)²⁶  and the normal mean percentage of BV⁺ CD4⁺ T cells in adult blood (mean ± SD are from a cohort of 85 normal specimens, according to Beckman Coulter). With the exception of BV 23 a markedly decreased number of BV⁺ CD4⁺ T cells were observed, particularly in patients with stage III/IV CTCL. (B) The combination of the reduction of absolute CD4⁺ values of specific BV subfamilies with a corresponding monoclonal spectratype profile reveals that a further depletion of BV 22⁺ CD4 T cells is actually present in this subfamily. An instructive example is shown.