Cloned mouse mast cells derived from immunized lymph node cells and from foetal liver cells exhibit characteristics of bone marrow-derived mast cells containing chondroitin sulphate E proteoglycan

Cloned mouse mast cells which were T cell growth-dependent were derived both from immunized lymph node and from foetal liver, and were found to be morphologically and biochemically similar to mast cells previously differentiated in vitro from mouse bone marrow (BMMC). These two T cell growth-dependent mouse mast cell clones were identical to the BMMC in their preferential synthesis of chondroitin sulphate E proteoglycan rather than heparin proteoglycan. The hydrodynamic size of the cell-associated proteoglycan from each of the three mast cell sources was 150,000-250,000 mol. wt.; and that of the covalently bound glycosaminoglycans was 13,000-25,000 mol. wt. Chondroitinase ABC digestion of the [³⁵S]proteolgycans from both cloned mast cells, as well as the BMMC, yielded only two disaccharides which comigrated on ascending thin layer chromatography with ΔDi-4S and ΔDi-diS(E) standards, respectively. Quantification of the radioactivity in the enzyme digests revealed that one-sixth to one-half of the resulting disaccharides were disulphated, similar to that found in BMMC containing chondroitin sulphate E. When sensitized with monoclonal IgE, washed, and subsequently challenged with specific antigen, each of the two cloned mast cells generated more than 100 ng of leukotriene C₄ (LTC₄)/10⁶ cells, but only 3-12 ng leukotriene B₄ (LTB₄)/10⁶ cells, characteristics also observed for the BMMC. Based upon these observations, it is concluded that the cloned mast cells from lymph node and liver and the bone marrow-derived mast cell belong to a distinct subclass of mast cells. These mast cells have been designated E-mast cells (E-MC) in order to distinguish them from heparin-containing mast cells (H-MC).