The use of protein as a carrier of methotrexate for experimental cancer chemotherapy. I. Preparation of pea seed lectin-methotrexate derivative and the preliminary experiments.

A method of preparation of pea seed lectin-methotrexate derivative by means of hydroxy-succinimide ester of methotrexate was elaborated. Five moles of methotrexate was bound to one lectin mole on the average as verified by analysis. For the distribution study lectin was labeled with 131I. Labeled lectin was administered intravenously to Yoshida sarcoma bearing rats and its distribution in the organism was monitored. After 24 hours the labeled lectin was entrapped predominantly in the reticuloendothelial system but after 48 and 72 hours the accumulation was seen also in thyroid, urinary bladder and tumor (1/4 cases only). The discrepancy in distribution of lectin in the tumor has been discussed.