Assay of Chlamydia pneumoniae-specific IgM antibodies by ELISA method--reduction of non-specific reaction and resetting of serological criteria by measuring IgM antibodies--.

In the present study, we tried to reduce the non-specific reactions for measuring anti-Chlamydia pneumoniae IgM antibodies by the ELISA kit of HITAZYME C. pneumoniae Ab-IgM (HITAZYME IgM) by using a new absorbent. We also tried to reset the IgM cut-off index (ID) of HITAZYME IgM by testing serum samples from healthy children and healthy adults with no respiratory symptoms. The results suggest that the use of the new absorbent (anti-human IgG antibodies) may reduce the non-specific reactions by rheumatoid factor and anti-nuclear antibodies, and that the setting of the higher cut-off ID (2.00), calculated as the mean ID+3SD of the serum samples from healthy children and healthy adults, respectively, would improve the specificity of IgM during the measurement by HITAZYME IgM.