Aberrant Ki-67 expression in normal bone marrow revealed by multiparameter flow cytometric analysis.

Ki-67 is a commercially available monoclonal antibody that reacts with a nuclear antigen detectable in proliferating cells only. Since its first description, it has been widely used as a "universal" proliferation marker and few groups have questioned the validity of the initially described reactivity, although this was tested only on very restricted experimental models. We wanted to check its reactivity on normal bone marrow (BM) samples using a multiparameter flow cytometric analysis. Although we were able to reproduce the findings of Ki-67 positivity on cultured and stimulated cells, we could not detect any convincing Ki-67 positivity on nuclei of normal BM samples. These samples all had a noticeable proliferating compartment as evidenced by their DNA content. These data are in contrast with the data we obtained starting from stressed marrows and marrows cultured in the presence of hematopoietic growth factors, where we found a marked Ki-67 positivity. This discrepancy suggests that bone marrow cells, growing and proliferating under steady-state conditions and guided by natural control mechanisms, may lose their Ki-67 expression upon exiting the progenitor compartment and entering the differentiating compartment.

[Sulfasalazine allergy: fever, skin rash, hepatitis and T-lymphocytes]. / Sulfasalazine-allergie: koorts, huidrash, hepatitis en T-lymfocytose.

We describe a case of severe sulfasalazine allergy. Exacerbation of the symptoms occurred after unintentional rechallenge with co-trimoxazole, indicating that the reaction was triggered by the sulphonamide component. The clinical picture consisted of generalised adenopathy, hepatitis, high fever and a maculopapular skin rash. A bone marrow biopsy and skin biopsy both showed noncaseating granulomas. The white blood cell count rose to 90.10(9)/l with 40% atypical lymphocytes (plasmacytoid). They were identified by flow cytometry as activated T lymphocytes.

Flow cytometric analysis of T-lymphocyte subpopulations in B-cell chronic lymphocytic leukemia: correlation with clinical stage.

Several authors have studied the T-lymphocyte subpopulations in B-cell chronic lymphocytic leukemia (B-CLL), but previous studies were performed after preceding enrichment procedures, which are known to cause selective losses of certain subpopulations. To correct for this deficiency we used flow cytometric analysis, which enabled us to measure subpopulations directly on total blood samples. We studied T-lymphocyte subsets with OKT monoclonal antibodies in 45 patients with B-CLL. Serum levels of IgG, IgA and IgM were assayed simultaneously and findings were correlated with clinical stage (Rai classification). The absolute number of CD4-positive cells decreased in more advanced Rai stages, while the absolute number of CD8-positive cells increased, resulting in a progressive reduction in CD4/8 ratio. Results from patients in stages with equal prognosis (Rai I and II, Rai III and IV) were similar and when these results were grouped the observed differences were highly significant and clearly correlated with all prognostic groups.