Telomeres and immune competency

Telomeres are essential for the integrity of chromosomes and for cellular replication. Attrition of telomeres occurs during DNA replication owing to the inability of conventional DNA polymerase to replicate chromosomal termini and the insufficient compensation for telomere loss by telomerase, an enzyme that synthesizes telomeric DNA. A number of genetic defects have been described in humans and in animal models that cause accelerated telomere attrition, in turn leading to severe phenotypes of hematopoietic and other proliferating cells. Telomere length, most frequently measured as an average value in heterogeneous peripheral blood leukocyte populations in humans, has been associated with a wide range of health conditions and diseases of immune and non-immune cells. Here, I review recent studies of telomere length dynamics with particular relevance to immune function.