Depletion of both FDC and FRC networks leads to depletion of CD8⁺ T cells in both RMs and SMs. (A) Immunofluorescent staining of CD8 (blue) and TUNEL (green) in LNs before and after CD4 T-cell depletion, showing that apoptosis level in CD8 population within LTs is elevated after CD4 depletion, which correlates with the depletion of blue staining CD8⁺ T cells. (B) Quantitative image analysis of the number of apoptotic CD8⁺ T cells (left panel) and the number of CD8 T cells (right panel) in RMs and SMs before and after receiving CD4-depleting antibody, showing that CD4 depletion leads to increased apoptosis in CD8⁺ T-cell populations, therefore depleting CD8 T cells. Bars represent the mean ± SEM; and the dotted lines, the timing of anti-CD4 antibody. All the comparisons are made between labeled time point and predepletion. Star color matches line color. ns indicates not significant. *P < .05. **P < .01. ***P < .001.