Abstract
6-mercaptopurine in amount of 50mg per kilogram of body weight was administered daily in the dd strain mice, starting on the same day when the various antigenic stimulations were given. Modified immunological responses of the mice were examined and the following results were obtained.
1. Impairment of the primary as well as the secondary antibody responses to heat-killed salmonella and sheed erythrocyte antigens was recognized in the drug-treated mice.
2. When ascites hepatoma cells of AH39 strain indigenous to rat were inoculated intraperitoneally into the drug-treated mice, the xenogeneic grafts showed an extended survival time of 10 to 13 days. On the contrary, in the neutral mice, the inoculated tumor cells were entirely rejected within 9 days after the transplantation.
3. The administration of the antimetabolite seemed to delay the rejection time of allogeneic grafts: mice of DK1 strain maintained on 6-mercaptopurine rejected the full-thickness skin grafts taken from C3H/HeN strain mice 15 to 21 days after the transplantation, in a remarkable contrast to the complete rejection of the grafts observed within 14 days in controls.
4. No acquired resistance to experimental typhoid was conferred to the drug-treated mice which had been immunized with attenuated live vaccines.
5. Electrophoretic analysis were attempted on sera taken from the mice which had been injected with standard antigens in addition to 6-mercaptopurine: a decrease in albumin contents with relative increase of β-and γ-globulin levels was confirmed. Total protein concentration of the serum, however, remained at the same level as the controls.
6. In the spleen and the lymph nodes of the mice inoculated with the antigens in addition to the immunosuppressive drug, only a few plasma cells were observed scattered around the atrophied germinal centers. Premature lymphoid cells named “lymphogonia”, which had been considered by some hematologists to be able to synthesize 19 S macroglobulin antibodies, were however noticed in number larger than normal.
