Tumor-associated macrophages as the primary source of lysozyme in the urine of mice bearing GPC-11, a transplantable reticulum cell sarcoma.

Large amounts of lysozyme accumulated in the serum and urine of (NZB X BALB/c)F1 mice with GPC-11, a transplantable reticulum cell sarcoma, type A. We separated GPC-11 cell suspensions on 20% Ludox HS gradients. (HS is one of the nine general grades of Ludox offered by du Pont de Nemours & Co., Wilmington, Del.) We did morphologic, functional, and biochemical experiments to detect oncogenic and enzymatic activity in each fraction. Oncogenic cells did not produce lysozyme. In contrast, macrophages associated with the solid tumor did produce lysozyme. The lysozyme purified from the GPC-11-associated macrophages resembled in size, electrophoretic mobility, and antigenicity the lysozyme purified from the urine of mice with the GPC-11 tumor.