Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Neuroimmunomodulation 2008;15:365–379 DOI: 10.1159/000156478 Variation Rhythms of Lymphocyte Subsets during Healthy Aging Ana Maria Caetano Faria a Sara Monteiro de Moraes a Ludmila Helene Ferreira de Freitas a Elaine Speziali a, d Taciana Figueiredo Soares b Suzane Pretti Figueiredo-Neves c Danielle Marquete Vitelli-Avelar e Marina Ângela Martins e Kátia Valéria Bastos Dias Barbosa h Eric Basseti Soares j Renato Sathler-Avelar e Vanessa Peruhype-Magalhães e, f, g Glenda Meira Cardoso f, i Fabiano Comin a Rosângela Teixeira h Silvana Maria Elói-Santos c, e Dulciene Maria Magalhães Queiroz c Rodrigo Corrêa-Oliveira f Moisés Evandro Bauer k Andréa Teixeira-Carvalho e, f Olindo Assis Martins-Filho e a Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, b Laboratório de Pesquisa em Bacteriologia and c Departamento de Propedêutica Complementar, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, d Núcleo de Pesquisa em Imunologia, Faculdade de Ciências da Saúde, Universidade Vale do Rio Doce, Governador Valadares, e Laboratório de Biomarcadores de Diagnóstico e Monitoração, f Laboratório de Imunologia Celular e Molecular and g Laboratório de Pesquisas Clínicas, Centro de Pesquisas René Rachou, FIOCRUZ, h Instituto Alfa de Gastroenterologia do Hospital das Clínicas da Universidade Federal de Minas Gerais, i Faculdade São Camilo and j Fundação Hemominas, Belo Horizonte, and k Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil in the frequencies of cells related to both innate and adap- tive immunity clearly occur with aging in these individuals. These changes were not progressive and equally steady for all cell populations tested but instead showed an oscillatory or rhythmic behavior that was distinctive of each population at different age intervals. We also observed that abrupt changes in the frequencies of immune cells may occur in healthy individuals over 75 years old, suggesting there is an impaired flexibility of the immune system at late stages of life to sustain homeostasis via immune mechanisms. We pre- sented reference ranges for healthy Brazilian individuals at all ages. The knowledge of these parameters in further detail will allow interventions to optimize immune function in ad- vanced age and to improve the quality of life in the elderly. Copyright © 2008 S. Karger AG, Basel Key Words Lymphocytes  Normal ranges  Aging  Immunosenescence  Flow cytometry Abstract Immunological alterations associated with aging (immu- nosenescence) do not represent a simple unidirectional de- cline in all functions but develop as a complex remodeling of the immune system, involving multiple reorganization and developmentally regulated changes. In general, most data available about aging were obtained at particular age intervals and most of them come from Caucasian individuals from either Europe or the United States. Here, we report the frequencies of major lymphocyte subsets in healthy Brazil- ian individuals from 2 distinct geographic regions (South- east and South) at several age intervals spanning a lifetime period (0–86 years). Overall, we demonstrated that changes Published online: November 26, 2008 Dr. Ana Maria Caetano Faria Laboratório de Imunobiologia, Departamento de Bioquímica e Imunologia Instituto de Ciências Biológicas, Avenida Antônio Carlos 6627 Belo Horizonte, Minas Gerais 31270-901 (Brazil) Tel./Fax +55 31 3409 2640, E-Mail afaria@icb.ufmg.br © 2008 S. Karger AG, Basel 1021–7401/08/0156–0365$24.50/0 Accessible online at: www.karger.com/nim