Editorial Volume 13, Issue 2 pp 1568—1570

Aging alters immune responses to vaccines

Age-associated changes in the germinal center of lymph nodes and spleens. The germinal center (GC) is a specialized microenvironment formed within secondary lymphoid tissues like the lymph nodes (LN) or spleen during infection or immunization. The GC is divided into two compartments: (1) the dark zone where B cells undergo proliferation and somatic hypermutation (SHM) and (2) the light zone where antigen is presented on follicular dendritic cells (FDCs) to B cells that will present to T follicular helper cells (Tfh) for selection. The process is regulated by T follicular regulatory cells (Tfr). After receiving these signals, the B cell will re-enter the dark zone to undergo further proliferation and SHM and will exit as memory B cells or high-affinity antibody secreting plasma cells. In aging, these processes are dysregulated. Not only is the microarchitecture of the spleen and LN physically restructured, it has been shown that there are fewer Tfh and proliferating GC-B cells while the number of follicular monocytes, granulocytes, and Tfr are increased resulting in a more suppressive repertoire with fewer class-switched plasma and memory B cells. This dysregulation partly explains why we see decreased infection and vaccination responses in older adults. Figure created with Biorender.com

Figure 1. Age-associated changes in the germinal center of lymph nodes and spleens. The germinal center (GC) is a specialized microenvironment formed within secondary lymphoid tissues like the lymph nodes (LN) or spleen during infection or immunization. The GC is divided into two compartments: (1) the dark zone where B cells undergo proliferation and somatic hypermutation (SHM) and (2) the light zone where antigen is presented on follicular dendritic cells (FDCs) to B cells that will present to T follicular helper cells (Tfh) for selection. The process is regulated by T follicular regulatory cells (Tfr). After receiving these signals, the B cell will re-enter the dark zone to undergo further proliferation and SHM and will exit as memory B cells or high-affinity antibody secreting plasma cells. In aging, these processes are dysregulated. Not only is the microarchitecture of the spleen and LN physically restructured, it has been shown that there are fewer Tfh and proliferating GC-B cells while the number of follicular monocytes, granulocytes, and Tfr are increased resulting in a more suppressive repertoire with fewer class-switched plasma and memory B cells. This dysregulation partly explains why we see decreased infection and vaccination responses in older adults. Figure created with Biorender.com