Arguing that Cytomegalovirus is Beneficial for Old Immune Systems

Researchers here make the intriguing argument that persistent cytomegalovirus (CMV) infection results in a better rather than worse immune system in old age, for at least some measures. This stands in opposition to the current consensus and broad range of evidence to show that much of the disarray of the aged immune system is due to CMV and similar latent viral infections. Too large a portion of the limited resources of the adaptive immune system becomes devoted to these foes, at a point in life when new T cells are created slowly, if at all. The thymus, where T cells mature, atrophies in later life, while the hematopoietic stem cell pool responsible for creating immune cells declines in function. A number of potential immunotherapies work by provoking the immune system into greater activity; these are largely blunt tools, and can have serious side-effects. The argument in here is a similar one, perhaps, that the presence of CMV is provoking the immune system, thus making the immune response more effective in some ways than might otherwise have been the case. A caution here is that mouse and human adaptive immune systems are quite different in their dynamics in late life, and this may well be an important difference in this context. In old humans very few new T cells arrive from the thymus, and most are produced from replication in existing populations. In old mice, a much larger fraction of T cells emerge from the thymus. If the effects of CMV involve both firing up t...
Source: Fight Aging! - Category: Research Authors: Tags: Daily News Source Type: blogs