Changes in the Structure and Cell Composition of Human Carinal Lymph Nodes during Aging

Abstract

Changes in the structure and cell composition of carinal lymph nodes were studied in humans during aging. Replacement of node parenchyma with fibrous connective tissue progressing with age was demonstrated. The medullary matter significantly prevailed over the cortical substance. The lymph nodes in the cortical substance were small and had no light centers; the concentration of mature CD20⁺ B cells was high; the paracortical area was fragmented and thinned and contained no CD4⁺ T helpers. Ki-67⁺ cells were absent in all structural components of the lymph nodes reflecting exhaustion of lymphopoietic function, which was determined by the replacement of the reticular tissue of the microenvironment with the connective tissue and by the absence of CD4⁺ T cells regulating cellular and humoral immunity. The disintegration of the reticular stroma in the sinus system that acts as a biological filter impairs the function of lymph purification.