Defensive Driving: Directing HIV-1 Vaccine-Induced Humoral Immunity to the Mucosa with Chemokine Adjuvants

Figure 2

The Peyer’s patch (PP) is the inductive site of GALT responses. M cells in the follicle-associated epithelium (FAE) of the PP directly sample luminal antigens and deliver them to antigen-presenting cells in the basolateral tissue. Dendritic cells (purple) may also stretch across the FAE and sample antigen directly. Antigen is presented to T cells (blue) within the PP. CD4⁺ T cells (blue) provide help to PP B cells (red). Within the subepithelial zone (SED), PP germinal centers (GC), T_FH induce T-dependent IgA class switching of BCRs. Similarly, isolated lymphoid follicles (ILFs) are also inductive sites of MALT responses. Activated lymphocytes can exit the PP via efferent lymphatics and traffic to the mesenteric lymph node (MLN) or lamina proria (LP), and return to the GALT from circulation. In the GALT, antibody-secreting cells (ASCs) secrete antibodies including dimeric IgA (dIgA) which are translocated into the lumen.