CXCR5-deficient and wild-type T cells produce similar levels of T helper cytokines and costimulatory molecules. The percentage of CD4⁺KJ1-26⁺ T cells expressing ICOS (A), IFN-γ (B), or IL-4 (C) was determined by flow cytometry on cells isolated from the dLNs at the time points indicated after immunization with OVA/CT. Recipient mice (Balb/c × 129SV) had received lymphocytes from either CXCR5^-/-DO11.10 mice (□) or CXCR5^+/+DO11.10 mice (▪) 1 day before immunization. (Mean + SD, 2 mice per group; similar results were obtained in 2 additional experiments).