The aim of the present study was to explore the diagnostic value of the immunophenotypic analysis of bone marrow mast cells (BMMC) in indolent systemic mast cell disease (SMCD) patients. For that purpose, a total of 10 SMCD patients and 19 healthy controls were analyzed. Our results show that BMMC from SMCD are different from normal BMMC with regard to both their light scatter and immunophenotypic characteristics. Accordingly, forward light scatter (FSC), side (90°) light scatter (SSC), and baseline autofluorescence levels were higher in BMMC from indolent SMCD patients than they were in control subjects. From the immunophenotypic point of view, the most striking findings were the constant expression of CD2 (P = .0001), CD25 (P = .0001), and CD35 (P = .06) molecules by BMMC from SMCD patients, markers that were absent from all normal controls. In contrast, CD71, absent in BMMC from indolent SMCD, was positive in BMMC from normal subjects. Although, slight differences between BMMC from SMCD patients and normal controls were found in several other markers, they did not reach statistical significance. In conclusion, our results show that simultaneous assessment of FSC/SSC and reactivity for the CD117, CD2, CD25, CD33, and CD35 forms the basis for the immunophenotypic characterization of BMMC from SMCD in adults and should be integrated with clinical and morphologic studies for the diagnosis of the disease.

The goal of the present paper was to define the immunophenotype of bone marrow mast cells (BMMC) from healthy controls and patients with hematologic malignancies (HM) based on the use of multiple stainings with monoclonal antibodies analyzed by flow cytometry. Our results show that BMMC from both groups of individuals display a similar but heterogenous immunophenotype. The overall numbers of BMMC are higher in the HM group of individuals (p = 0.08). Three patterns of antigen expression were detected: (1) markers constantly positive in all cases analyzed (CD9, CD29, CD33, CD43, CD44, CD49d, CD49e, CD51, CD71, CD117, and FcεRI), (2) antigens that were constantly negative (CD1a, CD2, CD3, CD5, CD6, CD11a, CD14, CD15, CD16, CD19, CD20, CD21, CD23, CD25, CD30, CD34, CD38, CD41a, CD42b, CD65, CD66b, HLA-DR, and CD138), and (3) markers that were positive in a variable proportion of cases – CD11b (50%), CD11c (77%), CD13 (40%), CD18 (20%), CD22 (68%), CD35 (27%), CD40 (67%), CD54 (88%) and CD61 (40%). In addition, BMMC from all cases explored were CD45+, and this antigen was expressed at an intensity similar to that of mature granulocytes.In summary, our results show that BMMC from both healthy controls and HM patients display a relatively heterogenous immunophenotype. Interestingly, we have observed clear differences between the immunophenotype of BMMC and MC from other tissues. This could be due either to the heterogeneity of human MC according to their tissue localization or to the sensitivity of the method used for antigen detection.

Bcl-2 protein plays a major role in the prevention of programmed cell death of differentiating cells. In the present study, the expression of cytoplasmic bcl-2 by human Bone Marrow Mast Cells (BMMC) from both normal and pathological bone marrow samples was examined. A total of 35 subjects corresponding to 9 healthy volunteers, 8 cases of adult indolent systemic mast cell disease (SMCD), 4 cases of pediatric mastocytosis (PM), 11 cases of hematological malignancies (HM), 2 cases of reactive bone marrow, and 1 case of mast cell leukemia (MCL) were analyzed. The expression of bcl-2 was studied using quantitative three-color flow cytometry. We also studied the molecular configuration of the bcl-2 gene and other relatives by Southern blot and polymerase chain reaction (PCR) in the MCL case. Bcl-2 expression was detected in BMMC from all samples analyzed. No significant differences on the expression of bcl-2 were detected between BMMC from healthy subjects and patients with SMCD, PM, HM, and reactive bone marrow. By contrast , bcl-2 protein was overexpressed in BMMC from MCL patient without gene rearrangement. Our results show that bcl-2 protein was constitutively expressed by BMMC. BMMC from MCL display overexpression of bcl-2, which could not be related to molecular rearrangements involving the bcl-2 gene. The expression of this protein by mature MC may play a role in the prevention of MC apoptosis and thus help to explain the long survival of these cells. The overexpression of bcl-2 by BMMC in MCL may help to explain their resistance to chemotherapy-induced apoptosis. Am.

In this study the expression of 'classically' considered lymphoid-associated antigens (CD2, CD3, CD4, CD5, CD7, CD8, CD10, CD19, CD20, and CD22) was explored both in peripheral blood (PB) and bone marrow (BM) mast cells (MC) in a case of systemic mast cell disease (SMCD) by means of using multiple stainings and a direct immunofluorescence technique. CD2 and CD22 were expressed in both PB and BM MC, all the remaining lymphoid-associated markers were negative. Our results suggest that the reactivity for both CD2 and CD22 in PB and BM MC would be aberrant.