Increased telomere length and proliferative potential in peripheral blood mononuclear cells of adults of different ages stimulated with concanavalin A.
BACKGROUND
Recently, a direct correlation with telomere length, proliferative potential and telomerase activity has been found in the process of aging in peripheral blood cells. The objective of the study was to evaluate telomere length and proliferative potential in peripheral blood mononuclear cells (PBMCs) after stimulation with Concanavalin A (ConA) of young adults compared with older adults.


METHODS
Blood samples were obtained from 20 healthy young males (20-25 years old) (group Y) and 20 males (60-65 years old) (group O). We compared PBMC proliferation before and after stimulation with ConA. DNA was isolated from cells separated before and after culture with ConA for telomeric measurement by real-time polymerase chain reaction.


RESULTS
In vitro stimulation of PBMCs from young subjects induced an increase of telomere length as well as a higher replicative capacity of cell proliferation. Samples from older adults showed higher loss of telomeric DNA (p = 0.03) and higher levels of senescent (≤6.2 kb) telomeric DNA (p = 0.02) and displayed a marked decrease of proliferation capacity. Viability cell counts and CFSE tracking in 72-h-old cell cultures indicated that group O PBMCs (CD8+ and CD4+ T cells) underwent fewer mitotic cycles and had shorter telomeres than group Y (p = 0.04).


CONCLUSIONS
Our findings confirm that telomere length in older-age adults is shorter than in younger subjects. After stimulation with ConA, cells are not restored to the previous telomere length and undergo replicative senescence. This is in sharp contrast to the response observed in young adults after ConA stimulation where cells increase in telomere length and replicative capacity. The mechanisms involved in this phenomenon are not yet clear and merit further investigation.
Unidad de Investigación en Epidemiología Clínica, Unidad Médica de Alta Especialidad (UMAE) No, 1 Bajío, Instituto Mexicano del Seguro Social (IMSS), León, Guanajuato, Mexico. bomo907@hotmail.com.
Blanca
B
Murillo-Ortiz
Froylán
F
Albarrán-Tamayo
Sergio
S
López-Briones
Sandra
S
Martínez-Garza
Luis
L
Benítez-Bribiesca
Diego
D
Arenas-Aranda
D000328:Adult; D000368:Aged; D000375:Aging / Q000187:drug effects* / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D059505:Telomere Homeostasis / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
D003208:Concanavalin A