Treatment of the murine lymphoma A31 with intravenous, sterilized, 114mIn-loaded A31 cells.

The effect on a mouse B-cell lymphoma (A31) of intravenously (i.v.) injected, sterilized, A31 lymphoma cells loaded with [114mIn]oxine was examined. The treatment of the B-cell lymphoma was started 14 days after the i.v. injection of 10(2) viable cells. The [114mIn]oxine-bearing gamma-ray sterilized A31 cells were injected at two dose levels either with 37 kBq on days 15, 22 and 27 (total dose 110 kBq) or 74 kBq on days 15, 16, 17, 22 and 27 (total dose 370 kBq). The smaller amount (110 kBq) of 114mIn activity did not extend the survival of mice when compared with non-treatment controls but the greater amount (370 kBq) produced a significant extension in survival. This survival time was longer than that produced by 370 kBq [114mIn]oxine without carrier cells, lethal total body irradiation (with bone marrow rescue), splenectomy at day 14 or a single injection on day 14 of a maximum tolerated dose of vincristine sulphate. The increase in survival time was thought to arise mainly from 114mIn held by spleen macrophages. The accumulated spleen dose by 7 days after the fifth of the five injections of 74 kBq was 167 Gy. At this dose level the spleen was hypoplastic and the red cells, white cells and platelets in the peripheral blood were severely, though not permanently, suppressed.