Elevated levels of serum CD5 antigen-like protein distinguish secondary progressive multiple sclerosis from other...

CD5 antigen-like (CD5L) protein is a macrophage-secreted protein with roles in immunomodulation and lipid homeostasis. We compared serum CD5L levels in healthy controls to individuals diagnosed with clinically isolated syndrome, relapsing remitting (RR), secondary progressive (SP), and primary progressive (PP) multiple sclerosis (MS). CD5L was increased in SPMS relative to controls, RRMS, and PPMS. SPMS CD5L was associated with longer disease duration independent of age, sex, or disease severity. The positive relationship between CD5L and disease duration in SPMS suggests a chronic peripheral inflammatory profile compared to other subtypes, particularly PPMS, warranting investigation of functional roles for CD5L in MS.