Ultrastructural, biochemical, and functional characteristics of histamine-containing cells cloned from mouse bone marrow: Tentative identification as mucosal mast cells

Two histamine-containing granulated cell lines were cloned from mouse bone marrow by using sequential soft agar and limiting dilution techniques. Concanavalin A-stimulated mouse spleen supernatants were required for cell proliferation. Cloned cell lines were Lyt-1.2, Lyt-2.2, Thy-1.2, surface Ig negative, I-A positive, and failed to ingest latex particles. Cells expressed 6.4 to 9.0 x 10⁴ IgE high affinity receptors and contained approximately 1 to 2 pg of histamine per cell. Electron microscopy revealed granule and surface membrane features characteristic of mast cells. The cloned histamine-containing granulated cell lines synthesized a proteoglycan containing glycosaminoglycan side chains with an estimated average m.w. of 40,000. The glycosaminoglycan side chains consisted only of chondroitin sulfates identified by charge characteristics and through the use of selective polysaccharidases. These cells degranulated to immunologic stimuli and the calcium ionophore A23187 but not to compound 48/80. Taken together, the above findings suggest that these histamine-containing granulated cell lines that are cloned from bone marrow are mucosal (atypical) mast cells.