We evaluated the ability of plasma adsorbed against
Sepharose, inactivated CNBr
Sepharose, or
protein A-Sepharose to inhibit the growth of primary mammary
carcinomas in Buffalo/N rats. Mammary
adenocarcinomas were induced by a single
intravenous injection of N-nitroso N-
methylurea. When palpable mammary
tumors were detected, rats were treated by infusion of plasma obtained from normal or
tumor-bearing rats. Animals were killed 50 days after entry into the experiment; the index mammary
tumor and any subsequently arising
tumors were weighed and examined histologically. Unadsorbed plasma obtained from normal or
tumor-bearing rats had no detectable antitumor effect. Normal plasma adsorbed against
Sepharose or
Sepharose derivatives had no significant antitumor effect. Weight (median) of index mammary
tumors in groups of rats treated with normal plasma adsorbed against
Sepharose alone, inactivated CNBr
Sepharose alone, or
protein A--Sepharose alone was not significantly different from weight of
tumors of untreated, control animals.
Tumor-bearer plasma adsorbed against either inactivated CNBr
Sepharose or
protein A-Sepharose had significant antitumor effect. Weight of index mammary
tumors in groups of rats treated with
tumor-bearer plasma adsorbed to inactivated CNBr
Sepharose alone or against
protein A-Sepharose alone was significantly less than weight of
tumors in control rats.
Tumor-bearer plasma adsorbed against
Sepharose alone inhibited
tumor growth in one experiment but not in a second experiment. Tests for
endotoxin in CNBr
Sepharose indicated the presence of approximately 1 ng
endotoxin/g
Sepharose. Administration of nanogram quantities of Salmonella enteritidis
endotoxin in saline did not inhibit growth of primary mammary
tumors. These experiments describe a rodent model that may be useful in the analysis of the basis of the inhibition of
tumor growth that occurs following administration of adsorbed plasma.