[Circadian rhythm of cellular and humoral immunologic parameters]

From 8 o'clock AM to 6 o'clock PM every two hours in 22 healthy volunteers the following examinations were done: 1. lymphocyte transformation test using the mitogens PHA, Con A and PWM, 2. immunosuppressive activity of the serum on the mitogen-induced lymphocyte transformation, 3. determination of the serum levels of cortisol and human growth hormone (hgH). In the morning the mitogenic lymphocyte transformation was on the lowest and at 4 o'clock PM on the highest level. In opposite to this the immunosuppressive activity of the serum an the serum level of cortisol reached the highest level in the morning and decreased to the minimum at 4 resp. 6 o'clock PM. These findings can be interpreted at least for these parameters in the meaning of a reduced cellular and humoral immunity in the first part of the day, which is confirmed from further results in the literature.