Related Experiment Video
Updated: Jun 8, 2026

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells
Published on: September 28, 2017
Circadian rhythmicity of lymphocyte subpopulations and relationship with neuro-endocrine system
G Mazzoccoli1, A De Cata, A Greco
1Department of Internal Medicine, Scientific Institute and Regional General Hospital, Foggia, Italy. g.mazzoccoli@tin.it
Abstract:
Lymphocyte subpopulations present circadian variation of some of their subsets, this variation may influence magnitude and expression of the immune responses and may be related to the variation of neuro-endocrine humoral factors. In our study cortisol, melatonin, TRH, TSH, FT4, GH, IGF1 and IL2 serum levels were measured and lymphocyte subpopulation analyses were performed on blood samples collected every four hours for 24 hours from 11 healthy male subjects aged 38-55 years. A clear circadian rhythm was validated for cortisol serum levels, CD8, CD16, TcRδ1 with acrophase in the morning and at noon, and for melatonin, TRH, TSH, GH, CD3, CD4, CD4/CD8 ratio, HLA-DR, CD20 and CD25 with acrophase at night. Changes of serum levels of FT4, IGF1 and IL2 did not show circadian rhythmicity. In the photoperiod (06.00-18.00h) and in the scotoperiod (18.00-06.00h) there were significant correlations among the lymphocyte subpopulations and humoral factors studied. The results show that specific lymphocyte subsets present different profiles of nyctohemeral changes and different timed relationships with neuro-endocrine hormones.
More Related Videos
Related Concept Videos
Circadian Rhythms and Gene Regulation
Circadian Rhythms and Gene Regulation
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Biological Clocks and Seasonal Responses
Lymphoid Cells and Tissues
Lymphoid cells consist of various types of immune system cells. These include B and T lymphocytes, which are responsible for producing antibodies and killing infected cells, respectively. Dendritic cells act as messengers between the innate and adaptive...
Functions of the Lymphatic and Immune System
The primary lymphoid organs, including the bone marrow and the thymus, serve as the maturation sites for lymphocytes. Secondary lymphoid organs, like the mucosa-associated lymphoid tissue, activate these lymphocytes and serve as...

