SEASONAL-VARIATION IN PERIPHERAL-BLOOD LEUKOCYTE SUBSETS AND IN SERUMINTERLEUKIN-6, AND SOLUBLE INTERLEUKIN-2 AND INTERLEUKIN-6 RECEPTOR CONCENTRATIONS IN NORMAL VOLUNTEERS

This study has been carried out in order to investigate seasonal varia tion in peripheral blood immune cells, such as leukocytes, monocytes, neutrophils, lymphocytes, CD3(+) T, CD4(+) T, CD8(+) T, CD25(+) T, CD2 0(+) B, and serum interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R) and sIL-2R levels in normal volunteers. Toward this end, 26 normal vo lunteers (13 men, 13 women) had monthly blood samplings during one cal endar year for peripheral blood count, flow cytometric enumeration of peripheral leukocyte subsets and immunoassays of IL-6, sIL-6R and sIL- 2R. It was found that most of the immune variables change rhythmically during the seasons as a group phenomenon. Statistically significant y early variations with seasonal rhythms, i.e. annual rhythms or harmoni cs, such as semiannual, tetramensual and trimensual rhythms, were foun d in the number of leukocytes, neutrophils, monocytes, lymphocytes, CD 4(+) T, CD8(+) T, CD25(+) T, CD20(+) B cells, in the CD4(+)/CD8(+) rat io, and serum IL-6 and sIL-6R levels. It is concluded that the immune system is characterized by a multifrequency time-structure with signif icant high-amplitude yearly variations in the number of some periphera l blood leukocyte subsets.