OTI cells induce CXCR3 expression on AFCs and GC B cells. Chimeras were constructed in CD45.2⁺ C57BL6 mice by transfer of CD45.1⁺ OTII cells or CD45.1⁺ OTII + OTI cells. These chimeras were immunized with alumOVA or alumPBS in both footpads, or left nonimmunized (NI). Seven days after immunization, cell suspensions were prepared from the 2 popliteal LN. The expression of CXCR3 and CXCR4 was assessed by flow cytometry on CD138⁺B220^int AFCs (A) and B220⁺GL7⁺Fas⁺ GC B cells (B). The numbers on FACS plots represent the percentages of AFC (A) or GC B cells (B) expressing CXCR3 or CXCR4. (C) Geometric mean ± SD of CD138⁺B220^int AFCs (left) and B220⁺GL7⁺Fas⁺ CG B cells (right) per popliteal LN in the different types of chimeras. These data are derived from 2-5 independent experiments with a total of 4-12 mice per group. (D) OVA specificity of FACS-sorted CXCR3⁻ or CXCR3⁺ AFCs isolated from, respectively, OTII-only or OTII + OTI chimeras day 7 after alumOVA, or of total AFCs from OTII + OTI chimeras NI or at 7 days after alumPBS in footpads was assessed by ELISPOT. Mean ± SD are representative of 3 independent experiments involving 6 mice per group. In both OTII-only or OTII + OTI chimeras immunized with alumOVA, one-third of the plated AFCs could be detected as OVA-specific, although none of the AFCs sorted from NI or alum-immunized OTII + OTI chimeras were detected as OVA-specific. The significance of differences is assessed by 2-tailed Mann-Whitney nonparametric statistics. NS indicates not significant.