Early expression of high-affinity receptor for immunoglobulin E (Fc∈RI) during differentiation of mouse mast cells and human basophils

Abstract

Immediate hypersensitivity is due to the release of mediators from mast cells and basophils after the crosslinking of Fc∈RI. The appearance of such receptors was examined during differentiation of human and mouse bone marrow cells cultured in the presence of IL-3. As already reported, mouse bone marrow yield cultures of > 95% mast cells by 3 wk, whereas human bone marrow develop into cultures comprising 25% basophils by 3 wk. Here we show that transcripts for Fc∈RI subunits and membrane-associated receptors are apparent by 1 wk in both human and murine IL-3-dependent bone marrow cells. These cells contain few, if any, granules. The expression of transcripts and the number of receptor-positive cells continue to increase over 3 wk of culture. In parallel, a progressively larger number of cells become increasingly granulated to finally resemble either basophils or mast cells. Mature peripheral human basophils also contain transcripts for Fc∈RI and, therefore, may have the potential to synthesize de novo receptors. The early appearance of Fc∈RI during cell differentiation may be important for these cells to respond to IgE-mediated stimuli before granulation. The physiologic role of Fc∈RI could be to mediate lymphokine production (IL-3, IL-4, IL-6, and granulocyte/macrophage colony-stimulating factor) without inducing cellular degranulation.