A recent study published in the Journal of Allergy and Clinical Immunology suggests that a soluble form of the immunoglobulin E (IgE) receptor, sFcεRI, could serve as both a biomarker of disease severity and a natural “brake” against severe allergic reactions in patients with systemic mastocytosis (SM).
MastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults. is characterized by the abnormal accumulation of mast cells in various organs. When these cells are activated by IgE, an antibody involved in allergic reactions, they release inflammatory mediators such as histamineHistamine A chemical released by mast cells when they are activated. Histamine causes many of the allergy-type symptoms in mastocytosis, including flushing, itching and hives..
Researchers noted that while elevated levels of sFcεRI are more common in advanced subtypes of SM, the data point to a potential protective mechanism: sFcεRI might help dampen life-threatening anaphylactic symptoms by intercepting IgE signals before they trigger an allergic reaction.
Read more about SM signs and symptoms
The study analyzed 189 serum samples from 114 patients with mastocytosis and 15 healthy individuals. The researchers observed that, while sFcεRI levels varied significantly among individuals, including healthy controls, there was a clear trend associated with disease severity. Patients with advanced SMAdvanced SM In these subtypes of SM, mast cells begin to damage organs. Advanced SM includes the subtypes aggressive SM, mast cell leukemia and SM with an associated hematological neoplasm. generally exhibited higher median protein levels than those with non-advanced forms. However, the study also highlighted high individual variations, noting that values can fluctuate significantly even within the same disease subtype.
The study demonstrated that patients with very high sFcεRI levels (>20 ng/mL) were less likely to experience vascular instability (a sudden, dangerous drop in blood pressure) or severe headaches. This supports the hypothesis that the body may produce sFcεRI to counteract severe IgE-dependent symptoms.
In laboratory tests, sFcεRI was also shown to inhibit the growth of neoplastic (cancerous) mast cells and to enhance the effects of KIT-targeting drugs such as midostaurin and avapritinib.
“The observation that sFcεRI is elevated in advanced SM may have clinical implications,” the researchers wrote. However, they cautioned that sFcεRI is not a universal prognostic marker, as some patients with highly aggressive mast cell leukemiaMast cell leukemia The most severe subtype of SM, caused by the rapid buildup of immature mast cells in the bone marrow and blood. Mast cell leukemia accounts for less than 5% of SM cases and has a poor prognosis. showed either normal or low levels of the protein.
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