title: Age-related changes in blood lymphocyte subsets of south Indian children.
abstract: BACKGROUND
  Enumeration of lymphocyte subsets has been widely used for the diagnosis and monitoring of several haematological and immunological disorders. Various studies have demonstrated age, sex and racial differences in lymphocyte subset expression. Reference values are not available for Indian children and there is a need for this information to replace commonly used, but inappropriate, adult lymphocyte subset ranges.
  
  
  METHODS
  One hundred thirty-eight healthy children between 3 and 15 years of age, attending a local government school in Chennai, South India were Included in the study. Haemoglobin levels, and total and differential cell counts were determined using an automated counter and lymphocyte subsets were analysed by flowcytometry.
  
  
  RESULTS
  The mean (SD) absolute lymphocyte count declined with age from 4338 (1031) at 3 years to reach a plateau of 3096 (914) at 11-13 years (p < 0.05). A significant decline was also observed in the absolute numbers of CD3+, CD4+, CD8+ and CD19+ cells. However, the percentage values of CD3+, CD4+, CD8+, CD16/56+ cells and the CD4/CD8 ratio remained fairly stable across the age range.
  
  
  CONCLUSIONS
  Our data would prove useful in interpreting disease-related changes in lymphocyte subsets in Indian children of different age groups. Age-related decrease in the absolute lymphocyte count as well as numbers of CD4 and CD8 cells was found to occur between the ages of 3 and 11 years. A normogram relating age to CD4 count has been developed.
authors.affiliation: HIV/AIDS Division and Immunology Division, Tuberculosis Research Centre, Mayor V.R. Ramanathan Road, Chetput, Chennai 600031, Tamil Nadu, India. doctorsoumya@yahoo.com
authors.forename: Soumya
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Luke Elizabeth
authors.initials: LE
authors.lastname: Hanna
authors.forename: Alamelu
authors.initials: A
authors.lastname: Raja
authors.forename: K
authors.initials: K
authors.lastname: Sankaran
authors.forename: Arun N
authors.initials: AN
authors.lastname: Kumar
mesh_terms: D000293:Adolescent / Q000502:physiology*; D000367:Age Factors; D000704:Analysis of Variance; D015703:Antigens, CD / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D007194:India / Q000453:epidemiology; D018655:Lymphocyte Count / Q000706:statistics & numerical data*; D008214:Lymphocytes / Q000097:blood*; D012016:Reference Values; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D015703:Antigens, CD