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Circadian variations in antigen-specific proliferation of human T lymphocytes and correlation to cortisol production

C Hiemke1, R Brunner, E Hammes

  • 1Department of Psychiatry, University of Mainz, Germany.

Psychoneuroendocrinology
|January 1, 1995
PubMed

Insights

Diurnal cortisol variations impact immune responses. Specifically, the body's response to tetanus toxoid (TT) decreased as cortisol levels rose, suggesting a link between natural cortisol rhythms and immune cell activity.

Area of Science:

  • Immunology
  • Endocrinology
  • Chronobiology

Background:

  • Cortisol is a known immunosuppressant in therapeutic use.
  • Endogenous cortisol production exhibits diurnal variations.
  • Understanding the impact of these natural cortisol fluctuations on immune function is crucial.

Purpose of the Study:

  • To investigate if diurnal variations in endogenous cortisol levels affect human lymphocyte proliferation responses.
  • To examine the relationship between cortisol levels and responses to mitogenic (phytohemagglutinin-A, PHA) and antigenic (tetanus toxoid, TT) stimuli.

Main Methods:

  • Eight healthy volunteers provided blood samples at 0200, 0600, 1000, and 1800h.
  • Plasma cortisol levels and lymphocyte proliferative responses (baseline, PHA, TT) were measured.
  • Proliferation was assessed using 3H-thymidine incorporation.

Main Results:

  • Cortisol levels showed typical diurnal patterns, peaking at 1000h and lowest at 0200h.
  • Lymphocyte proliferation stimulated by PHA or baseline activity did not fluctuate significantly throughout the day.
  • The response to tetanus toxoid (TT) decreased by 38% between 0600h and 1000h (p = .01).
  • Reduced TT response correlated significantly with increased plasma cortisol levels (p < .05).

Conclusions:

  • Diurnal variations in endogenous cortisol production may influence day-dependent changes in immune responsiveness.
  • The immune system's response to specific antigens, like tetanus toxoid, can be modulated by natural cortisol rhythms.

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