CD40LG and infectious mononucleosis: In a comparative study of two EIA tests (i.e., one recombinant CLIA and one purified native antigen+rVlsE ELISA; Marangoni et al., 2008), there was also a higher rate of false positive or equivocal results in the IgM isotype than in the IgG one, from 5% (1/22) in syphilis to 27% (3/11) in infectious mononucleosis for both tests.