TIME OF DAY OF ANTIGEN ENCOUNTER INFLUENCES THE MAGNITUDE OF THE IMMUNE-RESPONSE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 36  (2) , 347-354
Abstract
Studies in the rat and in man showed that the time of day at which an antigen is encountered has an influence on the expression of any subsequent cell-mediated immunity, when the response is measured after a fixed interval. Immune processes are apparently modulated by intrinsic biological rhythms. Experiments were reported in which sensitized rats were ear-challenged with oxazolone and studied at intervals during the delayed hypersensitivity reaction. Differences in the expression of immunity due to the clock time of challenge became apparent at an early stage and were still present after the maximum response, assessed by the change in ear thickness. The circadian variations in antigen responsiveness were present during the 2nd recall of immunity and could be manipulated by altering the lighting regimen. The light-dark cycle is often a synchronizer for biological rhythms, although its precise role in the oxazolone system remains to be evaluated. Phase reversal of the lighting regimen alters the proportions of lymphocytes present in rat blood at 2 clock times, one of which is the time of day at which the maximum immune response to oxazolone is initiated.