In order to further explore the cause of false‐positive, IgM and IgG antibodies of influenza virus, parainfluenza virus, Mycoplasma pneumonia, Chlamydia pneumonia, respiratory syncytial virus, adenovirus, and coxsackie virus were detected in seven serum samples, respectively, Also, rheumatoid factors (RF) and complement C1q were tested. This evidence concerns the gene CD40LG and chlamydia trachomatis infectious disease.