Expression of 67,000 MW calcimedin and its binding protein in resident and thioglycolate-elicited macrophages.

Calcimedins are newly recognized calcium-dependent hydrophobic-binding proteins. The 67,000 MW calcimedin exhibits calcium-dependent specific binding to a 60,000 MW intracellular acceptor protein (60,000 MW). Macrophages possessed 30,000 MW and 67,000 MW calcimedins and 60,000 MW acceptor protein, identified by immunofluorescence and confirmed by SDS-PAGE and Western immunoblots. Compared with low levels in resident macrophages, thioglycolate-elicited inflammatory macrophages showed large increases in the levels of 67,000 MW calcimedin and 60,000 MW acceptor protein, especially at cell-limiting membranes. Levels of calmodulin and 30,000 MW calcimedin appeared similar in both populations. Trypsinization removed most 67,000 MW calcimedin and some 60,000 MW acceptor-protein staining. The calcimedins appear to represent novel macrophage-differentiation antigens. Their modulation suggests that they may play a role in the inflammatory response.