High-sensitivity flow cytometric analysis of mast cell clustering in systemic mastocytosis: a quantitative and statistical analysis

Mast Cell Disease Assessment by Flow Cytometric Analysis

Mast cells are present at a low frequency in bone marrow, rendering high-sensitivity multiparametric flow cytometric analysis an ideal method to assess antigen expression on mast cells. This article discusses the normal antigen expression profile of mast cells, established criteria to identify neoplastic mast cells, and new immunophenotypic markers and approaches to identify the presence of neoplastic mast cells in cases of mastocytosis.

FLOCK cluster analysis of mast cell event clustering by high-sensitivity flow cytometry predicts systemic mastocytosis

OBJECTIVES

In our high-sensitivity flow cytometric approach for systemic mastocytosis (SM), we identified mast cell event clustering as a new diagnostic criterion for the disease.

METHODS

To objectively characterize mast cell gated event distributions, we performed cluster analysis using FLOCK, a computational approach to identify cell subsets in multidimensional flow cytometry data in an unbiased, automated fashion.

RESULTS

FLOCK identified discrete mast cell populations in most cases of SM (56/75 [75%]) but only a minority of non-SM cases (17/124 [14%]). FLOCK-identified mast cell populations accounted for 2.46% of total cells on average in SM cases and 0.09% of total cells on average in non-SM cases (P < .0001) and were predictive of SM, with a sensitivity of 75%, a specificity of 86%, a positive predictive value of 76%, and a negative predictive value of 85%.

CONCLUSIONS

FLOCK analysis provides useful diagnostic information for evaluating patients with suspected SM, and may be useful for the analysis of other hematopoietic neoplasms.

A fractal analysis of the spatial distribution of tumoral mast cells in lymph nodes and bone marrow

The spatial distribution of mast cells inside the tumor stroma has been little investigated. In this study, we have evaluated tumor mast cells distribution through the analysis of the morphological features of the spatial patterns generated by these cells, including size, shape, and architecture of the cell pattern. We have compared diffuse large B cells lymphoma (DLBCL) and systemic mastocytosis in two different anatomical localizations (lymph nodes for DLBCL and, respectively, bone marrow for mastocytosis). Results have indicated that, despite the high difference in size exhibited by the mast cells patterns in the two conditions, the spatial relationship between the mast cells forming the aggregates resulted similar, characterized by a significant tendency of the mast cells to self-organize in clusters.