CD4 and irritable bowel syndrome: IBS=Irritable Bowel Syndrome; FMS=Fibromyalgia syndrome; CRP=C-reactive protein; PLR=Platelet-lymphocyte ratio; HC=Healthy controls; FGIDs=Functional gastrointestinal disorders; CD3+=Cluster of differentiation 3+ T cells; CD4+=Cluster of differentiation 4+ T cells; MC=Mast cells; IBS-D=Irritable bowel syndrome with Diarrhea; IL2=Interleukin 2; IL8=Interleukin 8; IL10=Interleukin 10