Tissue distribution of rat macroglobulins in tumour-bearing rats.

Rat macroglobulins were determined in blood sera and extracts of tissues of intact rats and rats with Walker carcinoma by rocket immunoelectrophoresis. The serum levels of alpha1-macroglobulin (alpha1MG) alpha2-macroglobulin (alpha2MG) and pregnancy-associated alpha1-glycoprotein (alpha1PAG) were 1.86 +/- 0.07 mg/ml, 0.12 +/- 0. 02 mg/ml and 18.32 +/- 4.07 AU/ml respectively in control rats. Maximum concentrations of alpha1MG were found in heart, lung and spleen and lesser quantities were in liver and thymus, while alpha2MG and alpha1PAG were not found at all in tissue extracts from control rats. Serum alpha2MG and alpha1PAG concentrations increased more than 30-fold in tumour-bearing rats compared to control animals, while alpha1MG serum concentration was little changed. Increases in all three macroglobulins occurred in the tissues of tumour-bearing rats, particularly alpha1PAG. The tissue concentrations of alpha1MG and alpha2MG were similar and the tissue distribution was also similar with highest concentrations in heart and lung. Considerable quantities of the proteins were found in the tumour and part of peritoneum which made contact with the tumour. Changes in the protein concentrations in serum and tissue extracts of tumour-bearing rats suggest that all members of rat macroglobulin family are disturbed during the development of the Walker carcinoma, though only alpha2MG and alpha1PAG were substantially elevated.