[Basic and clinical studies on a new method for detecting anti-Mycoplasma pneumoniae antibody, using high density particles].

We developed a new method for detecting anti-Mycoplasma pneumoniae antibody, using high density particles (HDP). We characterized the HDP, and also studied the clinical applicability of the HDP agglutination method (HDPA). HDP were uniform, spherical particles, having a specific gravity of 2.0 and a mean particle volume of 18 fl. Adsorption of IgG by HDP was approximately 2 times that by polystyrene latex. The sensitized antigen to the HDP, extracted from the Mycoplasma pneumoniae (Mac strain) bound specifically to the anti-Mycoplasma pneumoniae antibody. With HDPA, the antibody was determined within 30 minutes, which was more rapid than with other routine methods such as complement fixation test, passive hemagglutination test and particle agglutination test (PA). HDPA showed excellent correlation with PA. However, the titers with HDPA were generally 2 to 5 tubes higher than that with PA. A follow-up study on 7 cases of mycoplasma pneumonia revealed remarkably high titers of anti-Mycoplasma pneumoniae antibodies in the acute phase of mycoplasma pneumonia by HDPA, compared to that by PA. HDPA is highly sensitive and specific test for detection of anti-Mycoplasma pneumoniae antibody, and useful for rapid diagnosis of mycoplasma pneumonia.