Factor XIII deficiency in BALB/c mice with plasmacytoma.

These studies examined the fate of Factor XIII (fibrin-stabilizing factor) in mice with plasmacytoma (MOPC-300, MOPC-384, MOPC-467, and J-558). Plasma Factor XIII levels in these mice decreased progressively with tumor expansion. No plasma inhibitors of Factor XIII activity could be detected. Factor XIII was found on plasmacytoma cell membranes and in the cytoplasm of the malignant cells by immunofluorescence. The inverse relationship between tumor load and plasma Factor XIII levels suggested that the fibrin-stabilizing factor was absorbed by the malignant cells.