Cell association of complexes of chymase, heparin proteoglycan, and protein after degranulation by rat mast cells
Schwartz, L.B.; Riedel, C.; Caulfield, J.P.; Wasserman, S.I.; Austen, K.F.
Journal of Immunology 126(6): 2071-2078
1981
ISSN/ISBN: 0022-1767 PMID: 6164718 Document Number: 177350
Complexes of chymase retain granule core material in cell surface labyrinths as demonstrated by EM. To solubilize and extract this core material, activated mast cells were washed with 1 M NaCl, a procedure that does not impair the integrity of plasma membrane barriers as assessed by the failure to release lactate dehydrogenase (LDH) from resting or activated mast cells. Resting cell high salt treatment caused swelling of cytoplasmic granules, whereas high salt treatment of activated cells caused the extruded granule core material to lose structure and become disassociated from the mast cell surface, as revealed by EM. Salt treatment of activated mast cells with anti-IgE also increased the net percent release ratios of CM and H to HXA from 0.17-0.76 and from 0.24-0.51, respectively, indicating either that complexes of H and protein were only partially solubilized by the high salt conditions or that there was some re-uptake after release. Net protein detected as released material from mast cells activated in a protein deficient medium with A23187 increased from 30-53 .mu.g/106 mast cells with salt treatment. Resting and activated mast cells have the same content of CM activity, 0.56 .+-. 0.15 U or 24 .+-. 6 .mu.g, indicating that there is no significant activation of enzyme precursor forms with mast cell activation and that CM accounts for .apprx. 40% of the secretory granule protein in these cells. H (28 .mu.g) and 1.3 U of HXA (< 1 .mu.g) were also detected in 106 mast cells. Thus, approximately 1/2 of the secretory granule proteins are functionally undefined, and these and the concentration and prolonged presentation of complexes containing H and CM at the cell surface of activated mast cells may be important in the chronicity of the host response to mast cell activation.