When combining demographic- and injury severity parameters with ‘clinical infection’ as our choice of infection marker, there were still brain-ECF cytokine levels independently associated with the development of a systemic infection (IL1-ra, G-CSF, PDGF-ABBB, MIP-1b and RANTES, p < 0.05 respectively) (Fig. 4A, B and Additional file 6). This evidence concerns the gene CCL4 and infection.