Fig. 1. Identification of clonal LLOp:I-A^b tetramer-binding T cells.

(A) LLOp:I-A^b tetramer-enriched CD4⁺ T cells from an uninfected (left panel) or a day 7 L. monocytogenes-infected B6 mouse with gates on CD44^low or CD44^high tetramer-binding cells. (B) Gates to identify LLOp:I-A^b tetramer-binding CXCR5⁻ PD-1⁻ Th1, CXCR5⁺ PD-1⁻ Tfh, and CXCR5⁺⁺ PD-1⁺ GC-Tfh effector cells (left panel) or memory cells (right panel). (C) CD45.1 versus CD45.2 expression by LLOp:I-A^b tetramer-binding cells from day 8 L. monocytogenes-infected B6 mice that received 7x10⁵ CD4⁺ T cells from 8 unique CD45 and CD90 congenic strains. (D) CD90.1 versus CD90.2 expression on cells expressing CD45.2/2 (red), CD45.1/2 (blue), or CD45.1/1 (green) identified as in (C) from 9 different mice. Cells of recipient origin were CD45.2/2 CD90.2/2. Donor-derived populations considered to be genuine (at least 5 events) are indicated with asterisks. (E) LLOp:I-A^b tetramer-binding CD4⁺ T cells in the spleens or lymph nodes of B6 mice after L. monocytogenes infection. Each dot is a value from a single mouse. Geometric mean values are shown with 95% confidence intervals in parentheses. (F) Number of donor-derived LLOp:I-A^b tetramer-binding cells derived from single naïve cells in each half of the spleen 7 days after L. monocytogenes infection. Lines connect values for the same clonal population. (G) Frequencies of Th1, Tfh, and GC-Tfh cells (as defined in (B)) in clonal LLOp:I-A^b tetramer-binding cell populations in halves of the same spleens. In (F) and (G), lines connect populations derived from the same naive cell. Representative data from single experiments are shown in (A-C). Pooled results from 2 independent experiments are shown in (E-G).