Location of IPCs within normal spleen. (A) Abundant 440c⁺ IPCs are evident in the periarteriolar sheet (PALS) and at the border of PALS with mantle-zone B cells. Serial histologic sections were stained with anti-CD3 (B), anti-B220 (C), and anti-IgD (D) to identify the T-cell and the B-cell zones in the white pulp. Rare IPCs are also visible in the red pulp. Original magnification, × 10.