FIGURE 1.
GC T cells (GC TFH) are distinct from TFH cells in their ability to produce IL-4. A and B, CD45.1+ SMtg CD4 T cells were adoptively transferred into C57BL/6 (B6)recipient mice subsequently infected with LCMV. A, SMtg CD4 T cells in spleen, day 8 postinfection. B, ICOS, PD-1, BTLA, and CXCR5 expression on SMtg cells; TFH cells are boxed. C, GL7 Ag and CXCR5 expression on nontransgenic CD44hiCD4 T cells, day 8 after LCMV infection. Non-TFH cells (CXCR5 −/lo), GL7−TFH cells (CXCR5hiGL7−), and GC TFH cells (CXCR5hiGL7+) are boxed. D, PD-1 expression on GC TFH, GL7−TFH, non-TFH, and naive CD4 cells. Data are representative of at least three independent experiments. E, Immunofluorescence histology of spleen, 8 d after CD45.1+ OTII CD4 T cell transfer and NP-OVA immunization. GL7 (green), CD45.1 (red), and B220 (blue). CD45.1+ CD4 T cells inside the GC are marked by white boxes, and representative CD45.1+ CD4 T cells outside the GC are marked by yellow boxes. Enlarged views of the boxed CD4 T cells are shown to the right. Original magnification × 200. F, Quantitation of GL7+ and GL7−CD45.1+ CD4 T cells outside GCs. G–P, mRNA expression by polyclonal LCMV-specific CD44hi CD4 T cells, day 8 postinfection. Non-TFH (CXCR5lo), TFH (CXCR5hiGL7−), and GC TFH (CXCR5hiGL7+) cells. Naive cells (CD4+CD44lo). Expression levels were quantitated in reference to β-actin mRNA and then normalized to naive CD4 T cells, except CXCR5, which was quantified by gene-expression microarray. G, Cmah. H, Bcl6. I, PD-1. J, ICOS. K, BTLA. L, CD200. M, IL-21. N, CXCR5. O, Prdm1/Blimp-1. P, IL-4. n = 2/group, with 10 spleens pooled per sample. **p < 0.01; ***p < 0.001.