FcRγ deficiency results in an increased accumulation of DN T cells.

<p><b>A.</b> B6.LPR.FcRγ^+/+ and B6.LPR.FcRγ^−/− mice were given 4×10⁷ CB6F1 splenocytes intravenously. After 7 days, varying numbers of DN T cells were purified and incubated for a further 3 days with irradiated CB6F1 splenocytes (10⁵/well), after which 1 µCi ³H-thymidine was added to each culture. Thymidine uptake, reflecting live proliferated cell number, was determined by scintillation counting. Two-way ANOVA p<0.0001; **Bonferroni post tests p<0.001. <b>B.</b> B6.SCID mice (FcRγ^+/+) received 10⁷ B6.LPR.FcRγ^+/+ (n = 3, upright triangles) or B6.LPR.FcRγ^−/− (n = 3, inverted triangles) DN T cells. On days 1, 5, 7, 10, and 14 blood samples were obtained and peripheral blood mononuclear cells (PBMCs) were stained for TCRβ, CD4, CD8, and NK1.1 expression. The percentage of DN T cells in the PBMC compartment was then determined by flow cytometry. Two-way repeated measures ANOVA p = 0.0279 for the effect of FcRγ genotype; Bonferroni post test p<0.001 at day 14. <b>C.</b> At day 7 and day 14, the splenocytes of the DN T cell recipients were counted and stained for TCRβ, CD4, CD8, and NK1.1 and examined by flow cytometry. The number of splenic DN T cells in each type of recipient was then determined. Two-way ANOVA p = 0.0005 for the effect of FcRγ genotype; Bonferroni post test p<0.001 at day 14.