Significant Associations Between Blood Cell Counts and Plasma Cytokines, Chemokines, and Growth Factors

The cytokine network plays a crucial role in regulating immune responses and facilitating intercellular communication. Cytokines are essential in numerous physiological and pathological processes. This study aimed to investigate associations between blood cell counts and a broad range of cytokines, chemokines, and growth factors. We included one hundred and sixty-five essentially healthy individuals in this study, which was approved by the Swedish Ethical Review Authority (Dnr 2015/378) and registered in EudraCT (2014-004235-39). Blood samples were collected for blood cell counts and analysis of cytokines, chemokines, and growth factors using the Proseek Multiplex Inflammation kit, Olink Bioscience, Uppsala, Sweden. Correlations between the different markers were calculated using Spearman rank correlations, adjusted for multiplicity and for multiple testing, with a significance threshold of <i>p</i> < 0.05. There were significant associations between platelet count and 23 cytokines, between white blood cell count and 8 cytokines, and between erythrocyte volume fractions and 19 cytokines. IL-6 had a central role within the cytokine network associated with platelets and was also associated with white blood cells and neutrophil cells. These findings emphasize the integrated nature of immune and hematological responses, where blood cell parameters are associated with systemic cytokine activity. The observed intercytokine associations, including cross-family interactions, may help to highlight regulatory pathways, providing potential targets for biomarker development and therapeutic intervention in immune-mediated conditions.