Spleen cell populations in normal and tumor-bearing hamsters.

Spleen cell subpopulations from normal and tumor-bearing hamsters (TBH) were quantified using Petri dishes coated with specific antibodies, and by flow cytometric immunofluorescence analysis. The relative numbers of T cells (Thy + cells) decreased, by both methods, as a function of tumor growth, while the number of B cells (bearing surface Ig) increased. Cells without T or B markers (null cells) were more numerous in the spleen of TBH and a large number of them expressed the receptor for the Fc fragment of IgG. Splenic cells were also sorted according to their light-scattering properties, and electron microscopic analysis was performed on the sorted fractions. It showed the presence of secreting plasmocytes and activated macrophages in the spleen of TBH.