Flow cytometric analysis of primary spleen cells. Spleen cells from a 4-month-old wild-type spleen (top row), a 4-month-old transgenic spleen from a founder line 37 (middle row), or a massively enlarged spleen from an ill, 5-month-old line 37 mouse were subjected to two-color flow cytometric analysis using an anti-TAg antibody and a variety of lymphoid markers. In the representative tumor shown in this figure, a significant proportion (≈60%) of the primary spleen cells are TAg⁺. The TAg⁺ cells are B220⁺, CD16⁺, and NK1.1⁺, but do not stain for CD4 or CD8.