Cultured human bone marrow-derived mast cells, their similarities to cultured murine E-mast cells

Homogenous populations of human mast cells were differentiated and grown by culturing bone marrow cells in the presence of conditioned medium derived from lectin-stimulated human peripheral blood mononuclear cells. The cells obtained were similar in ultrastructure, proteoglycan type and lipid products generated upon calcium ionophore A23187, and immunological activation to the murine E-mast cells (E-MC) differentiated in culture containing IL-3. Fluorescence analysis revealed that the human E-MC expressed IgE-Fc receptors which retained bound IgE through several washes. These cells did not express cell-surface lymphoid determinants (T11, T4, T8 and B4) and myeloid determinants 'My'. However, 40% of these cells expressed monocytic surface determinants, such as M-1. The amount of histamine that was found per 10⁶ cells was 525 ng ± 106 ng (mean ± SE, n = 4). These cultured mast cells possessed granular chondroitin sulphate E proteoglycan of about 180,000 MW. Following activation with either calcium ionophore A23187 or anti-IgE challenge, these mast cells released their preformed mediators and generated mainly leukotriene C₄, leukotriene B₄, and platelet-activating factor. In conclusion, according to all of these criteria these human cultured mast cells show many similarities to the murine cultured E-mast cells, and therefore could be considered as the culture analogue of the human intestinal E-mast cells identified recently.