CD40LG and Lyme disease: While the Centers for Disease Control and Prevention (CDC) has recommended two-tier testing for B. burgdorferi antibodies to diagnose Lyme disease—using first enzyme immunoassay (EIA) or immunofluorescence assay (IF) and then subsequent Western Blot for IgM and IgG on EIA or IFA-positive samples—this approach can lack sensitivity for the diagnosis of early B. burgdorferi infections, leading to false-negative results and underdiagnosis of Lyme disease (17).