Thymus cell subpopulations separated on discontinuous BSA gradients: Antigenic properties and circulation capacity

Subpopulations of thymus cells were separated on discontinuous bovine serum albumin (BSA) gradients. The cells in each fraction were tested for their sensitivity to the cytotoxic effect of normal guinea pig serum (GPS), and of antisera against the TL, θ, and H-2 alloantigens. The more buoyant fractions of strain A thymus cells were found to possess a high sensitivity to H-2 antibodies, but a low sensitivity to GPS, and to TL and θ-antisera. In contrast, high density A thymus cells were highly sensitive to the cytotoxic effect of GPS, TL-antibody and θ-antibody, and resistant to the cytotoxic effect of H-2 antibodies. Among subpopulations of C57BL thymus cells, GPS showed a marked different activity on buoyant and dense fractions. Subpopulations of thymus cells varied in their capacity to migrate to lymph nodes of isogeneic recipients. ⁵¹Cr-labeled cells of one of the more buoyant subpopulations showed the highest capacity of localizing in lymph nodes, whereas the densest cell subpopulation had the lowest capacity of migrating to lymph nodes.