For immunofluorescence, human tumor sections were incubated with anti-CD4 (1:200, ab133616, Abcam), anti-CXCR5 (1:200, ab46218, Abcam), anti-PD-1 (1:200, ab53587, Abcam), anti-CXCL13 (1:50, AF801, R&D), anti-IL-21(1:100, ab5978, Abcam), anti-CD8(1:500, ab237709, Abcam), and anti-CD20 (1:200, ab78237, Abcam) antibodies. The gene discussed is PDCD1; the disease is neoplasm.