Among patients with systemic mastocytosis (SM), a dysregulation, or imbalance, in B-cell and plasma cell compartments, along with distinctly modified antibody immune profiles based on subtype of disease, has been reported recently in The Journal of Allergy and Clinical Immunology.
SM includes a diverse group of disorders that take place because of clonal expansion of KIT-mutated abnormal mast cells. This, in turn, leads to accumulation of the mast cells in one or more organs or body systems, including the bone marrow, the gastrointestinal tract and the skin.
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In the present analysis, the researchers sought to explore the blood distribution of B-cell, plasma cell and antibody-isotype compartments in individuals with SM. They used flow cytometry to identify and measure B cells, plasma cells and their subsets in blood and bone marrow.
Euroflow-Immune Monitoring panel and Lymphocyte Screening Tube were utilized for their measurements. In all blood samples, the immunoglobulin (Ig) heavy chain isotypes and subclasses were evaluated with a cell surface membrane plus cytoplasmic staining.
A total of 108 consecutive adults with SM—64 women and 44 men—who had been diagnosed and classified based on the WHO 2022 criteria at reference centers of the Spanish Network on Mastocytosis were evaluated. The median patient age was 55 years.
Bone marrow samples were obtained from 31 individuals with SM and 17 controls. IgA, IgD, IgE, IgG and IgM plasma levels were calculated as well.
SM patients show dysregulation in B-cells and plasma
Results of the study revealed that compared with healthy donors, patients with SM exhibited a significant dysregulation in blood circulating B-cell and plasma cell compartments, as well as distinctly modified Ig-isotype profiles in plasma.
They reported finding different immune profiles based on diagnostic subtype of SM. In fact, the immune B-cell, plasma cell, and Ig-isotype profiles varied among individuals with bone marrow mastocytosis, indolent SM and advanced SM.
Individuals with SM exhibit signs of increased B-cell production and migration to tissues, which are linked to decreased plasma cell counts in blood, but to increased IgD, IgE or IgM antibody plasma levels. This results in “uniquely altered humoral immune profiles” in those with the previous three subtypes.
This is the first time that a significant dysregulation in the B-cell and plasma cell compartments in the blood obtained from patients with SM has been reported, in conjunction with distinctly modified antibody-isotype profiles in the plasma of patients with diverse SM subtypes.
“Further investigations are needed to better understand the precise underlying pathophysiological mechanisms involved in the alteration of the B-cell compartment in SM and its contribution to the variable clinical [behavior] of the disease,” the authors concluded.
