Separation of AKR mouse thymus lymphoma from normal thymic cells by centrifugal elutriation

The rapid separation of large numbers of viable thymus cells from AKR mice bearing transplanted or spontaneous thymic lymphomas was achieved by centrifugal elutriation. Separation of more than 3 × 10⁸ cells from either a transplanted lymphoma, designated 720, or from a spontaneous thymic lymphoma, required only 15 min. Unfractionated thymus cells obtained from mice bearing the transplanted lymphoma consisted of 80% lymphoma cells (by immunofluorescence for the viral protein, gp70) and 20% normal cells. Fractions of slowly sedimenting cells consisted almost exclusively of normal cells (95%) with modal volumes of 95 μm³. Fractions of rapidly sedimenting cells consisted of 95% tumor cells with volumes of 150-400 μm³. The slowly sedimenting cells were almost exclusively (98%) in the G₀- or G₁-phase. Fractions of rapidly sedimenting cells contained up to 55% S-phase and up to 30% G₂-phase cells. Intermediate fractions contained mixtures of normal cells and small G₀- or G₁-phase tumor cells. Thymidine uptake by the separated cells was determined. The fractions containing normal cells showed little thymidine uptake after 4 and 48 h in culture, while the fractions of tumor cells showed high levels of incorporation. In contrast to the high levels of thymidine uptake by the tumor cell fractions after 48 h in culture, there was little uptake by the unseparated cell suspension, suggesting a possible interaction between normal and tumor cells during the culture period.