Homeostasis and cell functions are remarkably influenced by cytokine signal network. Cytokine regulation is involved in many diseases, including cancer. ELISA method was used for the detection of soluble cytokines and co-stimulatory molecules in plasma of 30 blood donors in age range from 19 to 52 years (median 30,5; women 29, men 32). Most of the interleukin concentrations were below the detection limit of the assay. Because of problem of “zero” values (below detection limits), separate data evaluation of interleukin and other cytokine and co-stimulatory molecules (tumor necrosis factor-α, transforming growth factor β1, soluble CD23, CD40 ligand and IL-6 receptor) was made. Dependency between the parameters was tested using the Fisher’s exact tests for contingency table. The probability of the occurrence at detactable level for each particular interleukin was calculated, including the confidence interval for the probability. These results provide fundamental reference values of cytokine concentrations in plasma for identical observations on the patients with hematological malignancies. The cytokine or anti-cytokine therapy has already become a part of therapeutic protocols in treatment of malignant and non-malignant diseases.

        Key words: cytokines, interleukins, plasma concentration, blood donor, ELISA