CD40LG and multiple sclerosis: Previous studies have demonstrated that a CSF IgG index > 0.7 increases the likelihood of conversion to multiple sclerosis in individuals with clinically isolated syndrome.21,22 While quantitative IgG assessments have lower sensitivity than OCB, their specificity is notably higher in predicting conversion to multiple sclerosis.19,22 Incorporating CSF IgG and IgM indices increased the specificity of the criteria to 55.8% at 5 years, although sensitivity decreased to 77.3%.