Change of antigenic expression on rat tumor cells after their transplantation

Antigenic expression of 3-methylcholanthrene-induced transplantable fibrosarcoma KMT-17 cells was investigated in relation to days after ip transplantation. Cytotoxicity tests with antiserum against tumor-associated surface antigen of KMT-17 cells revealed that cytotoxic sensitivity and absorbing capacity decreased after transplantation, but they increased when other normal rats were given transplants of tumor cells. A decrease in the sensitivity was observed when immunosuppressively irradiated rats were given tumor transplants. Tumor cell density in the abdominal cavities of rats directly and absorbing capacity of KMT-17 cells to antiserum against the histocompatibility antigen did not change after transplantation. The possible mechanisms of antigenic change of KMT-17 cells were discussed.

Fast- and slow-growing transplantable tumors derived from spontaneous mammary tumors of the DBA/2 Ha-DD mouse

Nineteen transplantable tumor lines were established from individual spontaneous mammary tumors of the DBA/2 Ha-DD mouse. Of these lines, 5 were classified as fast growing, 8 as medium growing, and 6 as slow growing, based on the time required for the tumors to reach a size of 10 mm in average diameter and on the average survival time of tumor-bearing syngeneic hosts. The relative differences in rate of growth among 5 of these lines remained stable during 11 to 19 transplant generations. In DBA/2J mice, a slow-growing and a fast-growing tumor line were cross-immunogenic. The differences in growth rate between these 2 tumor lines were not primarily related to differences in immunogenicity since they were not abolished in preirradiated hosts. The growth of cell populations from these 2 tumor lines in culture was comparable; however, cells from the fast-growing line had a plating efficiency about 4 times higher than those from the slow-growing line.

Inhibition of metastasis in rats immunized with xenogenized autologous tumor cells after excision of the primary tumor

Subcutaneously transplanted 3-methylcholanthrene-induced KMT-17 tumor in WKA rats yielded not only a local solid tumor but also frequent metastases in regional lymph nodes. Neither active immunization with xenogenized identical tumor cells nor surgical excision of the solid tumor prohibited the metastases when each treatment was given 4 days after tumor transplantation. However, immunization combined with surgery significantly decreased the metastases and prolonged survival.

Effect of antimyeloma cell antiserum on immunological enhancement

Growth of Sarvoma 180 in AKR mice was enhanced by immunization with frozen-thawed homogenates of this tumor. Treatment of host mice with rabbit antimyeloma cell antiserum, either furing immunization or shortly after tumor implantation, resulted in a decreased incidence of tumor rejection or an increased rate of tumor growth. A slow-growing subline from a spontaneous, DBA/2Ha-DD mammary tumor is rejected after initial growth in DBA/2J mice. The incidence of rejection was reduced by treatment with the antiserum studied.