Similar distribution of i.p.- and i.n.-primed antigen-specific CD8⁺ T cells within the MLN. C57BL/6 mice were infected i.n. with x31-OVA_I and, 30 d later, were infected i.p. with WSN-OVA_I. To distinguish i.p.- and i.n.-primed CD8⁺ T cells, CD90.1⁺ or CD45.1⁺ naive OT-1 cells were transferred into recipient mice 1 d before each infection, respectively. MLNs were harvested, embedded in OCT, and frozen at day 14 after i.p. challenge. (A) Frozen sections were stained with each congenic marker to visualize i.p.- or i.n.-primed antigen-specific CD8⁺ T cells (green) and with antibodies to CD3, CD11c, or CD19 (red) to visualize total T cells, dendritic cells/macrophages, or B cells, respectively. Images are representative of three mice analyzed in two independent experiments (B).