CD40LG and systemic sclerosis: In a previous study, levels of IgG and IgM ACA were significantly higher in patients with definite SSc as compared to patients with very early SSc.31 However, in patients with very early SSc, only IgG ACA levels could predict the evolution to a definite SSc,31 highlighting that IgG levels might be more relevant as compared to other isotypes to delineate the prognosis.