Antibody response to Chlamydia pneumoniae infection in children with respiratory illness

Serologic diagnosis of Chlamydia pneumoniae infection has been based on the microimmunofluo-rescence test (MIF). However, recent prospective studies in children have found that 50 % infected with C. pneumoniae failed to develop any antibodies detectable by MIF. In this study, single sera from 46 culture-positive and 42 culture-negative children with respiratory infection and known MIF status were examined by immunoblotting. Forty-one (89.1%) of the single sera from culture-positive and 27 (64.3%) from culture-negative children reacted to C. pneumoniae antigens in immunoblot. C. pneumoniae proteins most frequently recognized by sera from culture-positive patients were at 101–102, 72–76, 50–52, 48–49, 43–44, 41–42, and 30–31 kDa. However, there did not appear to be a correlation of specific band patterns and culture status. California, San Francisco (J. Schachter) and at the University ofChlamydia pneumoniae is a common cause of acute and Arkansas, Little Rock (R. Rank), against the prototype isolate TWchronic respiratory infections in children and adults, including 183, using specific anti-IgG conjugate. The criteria forpneumonia and bronchitis [1, 2]. The diagnosis of C. pneumo-C. pneumoniae diagnosis proposed by Grayston et al. [2] were asniae infection is usually based on isolation of the microorgan-follows: An acute infection was defined as a 4-fold rise in IgGism in cell culture or on antibody detection using the microim-titer or an IgG titer of ⁄1:512, past infection was defined as a