CD4 / CD8 T Cell Ratio as a Measure of Immune Aging

The state of the aged adaptive immune system can be assessed in a practical way in animal studies, such as via exposure to influenza or other well-calibrated infectious disease. This assessment is also carried out on the human population as a whole in every influenza season, but for individual humans one wants a metric that is a little less do or die. The adaptive immune system is made up of many different subtypes of B cell and T cell, each serving a different purpose. While the overall population of T cells remains fairly consistent with age, the size of different T cell subtype populations changes in characteristic ways. Based on this, metrics of immune function can be created. T cells are characterized by the surface markers they expose, and the number of cells with a given marker or combination of markers can be counted in a flow cytometry machine, given a blood sample to work with. There are a very large number of these markers, and countless combinations, but some are established to be much more important than others. CD4 is a marker of T helper cells, which serve a variety of coordinating roles in the immune response, for example, while CD8 is a marker of cytotoxic T cells, responsible for killing errant cells and pathogens. This is an overly simplistic description of a very complex array of cell states and behaviors, but it is useful, as demonstrated by the fact that the CD4/CD8 ratio of T cells in a blood sample does, on balance, reflect the state of the immu...
Source: Fight Aging! - Category: Research Authors: Tags: Medicine, Biotech, Research Source Type: blogs