Subpopulações de linfócitos: intervalo de referência e associação com idade, sexo, hábitos de vida e sintomas de depressão e ansiedade em participantes do Estudo Longitudinal de Saúde do Adulto – ELSA-BRASIL

Abstract

There is interest in determining subpopulations of T and B lymphocytes and natural killer (NK) cells, as these values are used in the diagnosis and monitoring of therapy in a wide variety of clinical conditions, such as primary and acquired immunodeficiencies. Most reference ranges for lymphocyte subpopulations used are based on data from other countries. Studies suggest that lymphocyte subpopulations may be influenced by factors such as age, sex, lifestyle habits, and emotional disorders such as anxiety and depression. The objective of this study was to establish reference ranges for lymphocyte subpopulations in peripheral blood and evaluate potential variations by sex and age group, as well as to assess the distribution of lymphocyte subpopulations and their association with lifestyle habits, chronic diseases, depression, and anxiety in participants of the Longitudinal Study of Adult Health – ELSA-Brasil. Lymphocyte subpopulations from 351 participants were analyzed using a Sysmex XN-3000 automated hematology analyzer and a FACSCalibur four-color flow cytometer. Reference intervals were established using the 2.5th and 97.5th percentiles. The Z-score was used to assess the need for different reference intervals by sex and age group. The Mann-Whitney test, with a significance level set at p < 0.05 and 95% CI, was performed to identify differences between population groups. We used robust regression analysis to estimate the association of lymphocyte subpopulation counts with age, sex, body mass index, smoking, alcohol use, physical activity, diabetes, and hypertension. The defined reference intervals were: total lymphocytes (x10³/μL): 1.0–2.9; T lymphocytes: 721.0–2311.5 cells/μL, 59.1–84.5%; T helper lymphocytes: 421.4–1523.8 cells/μL, 32.5–61.6%; cytotoxic T lymphocyte: 175.3–879.8 cells/μl, 12.3–39.1%; helper T lymphocyte/cytotoxic T lymphocyte ratio: 0.8–4.1 cells/μl; CD19+ B lymphocyte: 85.2–501.6 cells/μl, 5.6–21.0%; NK cells: 83.9–444.4 cells/μl, 4.3–23.5%. Significant differences were observed in the relative and absolute values of most lymphocyte subpopulations regarding sex and age. After adjustments, it was demonstrated that with increasing age, there was a reduction in total lymphocytes, T lymphocytes, helper T lymphocytes, cytotoxic T lymphocytes, and B lymphocytes, and an increase in NK cells. Women showed an increase in helper T lymphocytes, the helper T lymphocyte/cytotoxic T lymphocyte ratio, and B lymphocytes, while decreasing NK cells. Obesity also showed an increase in total lymphocytes, T lymphocytes, helper T lymphocytes, cytotoxic T lymphocytes, and B lymphocytes. Finally, smoking was associated with an increase in total lymphocytes, T lymphocytes, helper T lymphocytes, and B lymphocytes. In depression, significant differences were observed in the relative values of T lymphocytes and helper T lymphocytes and in the absolute and relative values of NK cells. The results suggest that lymphocyte subpopulations may be influenced by sex, age, smoking, and obesity, highlighting the need for separate reference ranges for men and women, particularly for helper T lymphocytes, B lymphocytes, and NK cells.