Human bone marrow mast cells from indolent systemic mast cell disease constitutively express increased amounts of the CD63 protein on their surface

Abstract

The quantitative measurement of the expression of both cytoplasmic and surface CD63 antigen by human mast cells from both normal and pathological bone marrow samples was studied by use of flow cytometry. Our major goal was to analyze whether in vivo CD63 expression by human bone marrow mast cells could be useful to discriminate bone marrow mast cells from patients with mastocytosis from other conditions. For that purpose, a total of 65 subjects corresponding to 12 healthy volunteers, 25 B‐cell chronic lymphoproliferative disorders, 5 reactive bone marrow samples, 4 myelodysplastic syndromes, and 19 mastocytosis were analyzed. The expression of both surface and cytoplasmic CD63 by human bone marrow mast cells is clearly demonstrated. Our results show that high amounts of CD63 are present in human bone marrow mast cells most of it corresponding to an intracellular localization. No significant differences in CD63 expression were observed as regards both total and cytoplasmic CD63, except for higher CD63 levels in adult patients with mastocytosis (P = 0.05). By contrast, the mean level of surface CD63 significantly varied between the different groups of individuals. Accordingly, patients with monoclonal gammopathies displayed a slight decrease (P = 0.1) in surface CD63 expression, whereas bone marrow mast cells from adults with indolent systemic mast cell disease showed significantly (P = 0.0005) higher levels of surface CD63 as compared to healthy controls. Cytometry (Comm. Clin. Cytometry) 34:223–228, 1998. © 1998 Wiley‐Liss, Inc.

LAMP‐1 and LAMP‐2, but not LAMP‐3, are reliable markers for activation‐induced secretion of human mast cells

“…Further, LAMP-1 and LAMP-2 are proposed as activation markers of normal skin mast cells, although it must be taken into consideration that the activation-induced translocation of these molecules to the plasma membrane is a process that is restricted in time. On the basis of the present findings with activated skin mast cells, the increased expression of LAMP-3 in indolent mastocytosis bone marrow mast cells (10) suggests that these cells are activated in the context of the disease.…”

“…Interestingly, expression of LAMP-3 was increased in mast cells of patients with indolent mastocytosis (10). Reasons for this are unclear, but a thorough, systematic analysis of LAMPs regarding their expression and turnover after appropriate stimulation of human mast cells, as done here, might shed light on this question.…”

“…Thus far, expression of LAMP-3 has been reported in human bone marrow mast cells and in the leukemic human mast cell line 1 (HMC-1) (10,11). Interestingly, expression of LAMP-3 was increased in mast cells of patients with indolent mastocytosis (10).…”

Immunophenotypic analysis of mast cells in mastocytosis: When and how to do it. Proposals of the Spanish Network on Mastocytosis (REMA)

“…Among other features, pathologic MCs show aberrant expression of CD25 and CD2 (3) and abnormally high levels of the CD11c and CD35 complement receptors (8), the CD59 complement regulatory molecule (8), the CD63 lysosomal membrane antigen (9), and the CD69 early-activation antigen (10). In addition, MCs from mastocytosis express abnormally low levels of CD117 (stem cell factor receptor) and unexpectedly high light scatter and autofluorescence characteristics (3).…”

“…In contrast, other markers are expressed consistently by human MCs, but quantitative differences exist between normal and pathologic MCs with abnormally high-CD59, CD63, and CD69 -or low-CD117-amounts being detected in mastocytosis. For the first group of markers, objective and reproducible criteria for positivity are required; for the second group, accurate quantitative estimation of the amount of antigen expressed per cell is a prerequisite for obtaining reproducible results (9,16,17).…”