Figure 2.

CD4 depletion impairs the germinal center responses in HIV-vaccinated rhesus macaques. Inguinal lymph nodes from CD4d, Imm and NI rhesus macaques were biopsied at week 18 following immunization to visualize and measure GCs, and enumerate CD3+CD4+PD1+ T follicular helper cells (Tfh) and IgG+/IgM+ plasma cells in 200X random fields by immunofluorescence staining. (A) Representative images of lymph nodes looking at proliferating GCs labeled with PCNA (white), IgD (green), and CD20 (red). (B) Representative images of CD3+CD4+PD1+ Tfh inside and outside the GCs of lymph nodes. CD4 (white), CD3 (green) and PD1(red). (C) Representative images of IgM⁺ and IgG⁺ plasma cells in lymph nodes identified by CD20 (white), IgG (green), and IgM (red). Representative pictures at 200x magnification. Scale bar represents 100 mm. (D) CD4+ T cells were measured by flow cytometry at week 18 in the inguinal lymph nodes. (E) HIV Env-specific CD4+ Tfh cell response at week 34 in peripheral blood in the CD4d group at weeks 34, 2 weeks after the last immunization was determined by AIM assay and indicates fold increase in the frequency in gp140 stimulated cultures over that in unstimulated cultures. Significance was calculated with two-tailed unpaired Student’s t-test. p < 0.05 was considered significant.