Low alpha 2-macroglobulin-proteinase complex binding: a common but not exclusive characteristic of malignant cells.

: 125I-labelled alpha 2-macroglobulin complexed with trypsin bound to human cancer cell lines (HTB 144, CRL 1427, CCL 30, HB 8065, CCL 2, CRL 1593) but to a lesser degree than to normal cells. Malignant transformation of murine BALB/c 3T3 cells with Kirsten sarcoma virus caused a 50% reduction in the alpha 2-macroglobulin-trypsin complex binding. Two cloned revertants derived from the malignant BALB/c 3T3 cells did not induce tumors upon syngrafting. One exhibited normal binding and the other reduced binding. A reduced alpha 2M-proteinase complex binding is thus common in tumor cells but is not a unique property of the malignant state.