A timetable of 24-hour patterns for human lymphocyte subpopulations

Gianluigi Mazzoccoli, R. B. Sothern, A. De Cata, F. Giuliani, A. Fontana, M. Copetti, F. Pellegrini, R. Tarquini

Research output: Contribution to journalArticlepeer-review


Specific lymphocyte cell surface molecules involved in antigen recognition and cell activation present different circadian patterns, with peaks and troughs reflecting a specific time-related compartment of immune cell function. In order to study the dynamics of variation in expression of cytotoxic lymphocyte cell surface molecules that trigger immune responses, several lymphocyte cell surface clusters of differentiation (CD) and antigen receptors, analyses were performed on blood samples collected every 4 h for 24 h from eleven clinically-healthy men. Assays for serum melatonin (peaking at night) and cortisol (peaking near awakening) confirmed 24-h synchronization of the subjects to the light-dark schedule. A significant (p≤0.05) circadian rhythm could be demonstrated for six of the 10 lymphocyte subpopulations, with midday peaks for CD8+dim (T cytotoxic cells, 11:15 h), γδTCR (gamma-delta T cell receptor-expressing cells, 11:33 h), CD8+ (T suppressor/cytotoxic cells, 12:08 h), and for CD16+ (natural killer cells, 12:59 h), and peaks during the night for CD4+ (T helper/inducer cells, 01:23 h) and CD3+ (total T cells, 02:58 h). A borderline significant rhythm (p = 0.056) was also observed for CD20+ (total B cells), with a peak late in the evening (23:06 h). Acrophases for 3 subsets, CD8+bright (T suppressor cells, 15:22 h), HLA-DR+ (B cells and activated T cells, 23:06 h) and CD25+ (activated T lymphocytes with expression of the α chain of IL2 receptor, 23:35 h), where a 24-h rhythm could not be definitively determined, nevertheless provide information on the location of their highest values and possible physiological significance. Thus, specific lymphocyte surface molecules present distinctly-timed profiles of nyctohemeral changes that indicate a temporal (i.e., circadian) organization of cellular immune function, which is most likely of physiological significance in triggering and regulating immune responses. Such a molecular cytotoxic timetable can potentially serve as a guide to sampling during experimental, diagnostic, therapeutic and/or other medical procedures.

Original languageEnglish
Pages (from-to)387-395
Number of pages9
JournalJournal of Biological Regulators and Homeostatic Agents
Issue number3
Publication statusPublished - Jul 2011


  • γδTCR
  • CD16
  • CD8dim
  • Circadian rhythm
  • Cytotoxic lymphocyte

ASJC Scopus subject areas

  • Oncology
  • Endocrinology, Diabetes and Metabolism
  • Physiology (medical)
  • Immunology and Allergy
  • Immunology
  • Endocrinology
  • Physiology
  • Cancer Research


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