CLL phenotype cells in normal individuals are phenotypically identical to clinical CLL cells.

The comparison of antigen expression is shown between clinical CLL samples (n = 108), CLL phenotype cells from normal individuals (n = 10), and the residual polyclonal B lymphocytes from individuals with CLL phenotype cells present (n = 10). Clinical CLL samples at presentation were analyzed as part of their routine diagnosis. Apart from CD38 expression, the clinical CLL cells and the CLL phenotype cells from normal individuals show a very similar phenotypic profile, which is distinct that from normal B lymphocytes. (A) The percentage of B cells expressing CD38, which has a bimodal distribution in presentation CLL. Cases showing more than 30% expression have a poor prognosis.33 Fewer than 10% of the CLL phenotype cells present in normal individuals express CD38, suggesting an indolent phenotype. The residual B lymphocytes express variable levels of CD38. (B) The percentage of B cells expressing CD10, CD11a, CD23, CD5, and CD27. CD10 is not detected on circulating normal or CLL phenotype B cells. CD11a is expressed weakly by clinical CLL cells and CLL phenotype cells from normal individuals, whereas normal B lymphocytes are virtually all positive. In contrast, the majority of clinical CLL cells and CLL phenotype cells from normal individuals express CD5, CD23, and CD27, whereas a variable proportion of normal B lymphocytes express these antigens. (C) The fluorescence intensity for CD20, CD22, and CD79b is shown. These antigens are expressed by all 3 B-cell types, but the level of expression differs. Thus, clinical CLL cells and CLL phenotype cells from normal individuals express very low levels of CD20, CD22, and CD79b, whereas all 3 antigens are expressed at a much higher level by normal B lymphocytes.