We previously published the findings of a single-centre study examining three markers associated with immune dysfunction [3], namely neutrophil CD88 (as a marker of C5a-mediated neutrophil dysfunction [10, 11]), monocyte human leucocyte antigen-DR (HLA-DR) (as a marker of monocyte deactivation [12, 13]) and the proportion of regulatory T cells (Tregs, associated with an increased risk of secondary infection [14]). This evidence concerns the gene C5AR1 and immune system disorder.