Antibodies in bronchial secretions following natural infection with Mycoplasma pneumoniae

A micro-capture ELISA for detecting Mycoplasma pneumoniae IgM: comparison with indirect immunofluorescence and indirect ELISA

A mu-capture ELISA was developed for detecting Mycoplasma pneumoniae-specific IgM, and compared with an indirect immunofluorescent antibody (IFA) technique and an indirect ELISA. mu-capture ELISA and IFA compared well and were found to be the most sensitive assays. The IFA test can be completed in 2 h whilst the results of the mu-capture ELISA can be available in 24 h. Both tests are amenable to routine diagnostic use and have similar sensitivity. Indirect ELISA was found to be less sensitive and less specific, giving high assay values with several sera having undetectable M. pneumoniae CF antibody or CF antibody in low titre. Serum samples obtained from 11 patients at various times after M. pneumoniae infection showed maximum antibody levels within the first month by all assays, with a gradual fall in amount of IgM with time when assayed by mu-capture ELISA, a more gradual decline by IFA and hardly any decline with indirect ELISA. It was concluded that the indirect ELISA is unsuitable for the investigation of possible M. pneumoniae infection because the sustained high assay values with serum samples taken many months after infection, make interpretation of the test results very difficult.

Demonstration of antibodies to Mycoplasma pneumoniae attachment protein in human sera and respiratory secretions

Antibodies specific to the attachment protein of Mycoplasma pneumoniae were demonstrated in sera and respiratory secretions of human patients. The results indicate that the attachment protein is a major immunogen.

Hemadsorption and virulence are separable properties of Mycoplasma pneumoniae

A selective enrichment technique was used to isolate a hemadsorption-positive revertant of a hemadsorption-negative mutant strain of Mycoplasma pneumoniae. This hemadsorption-positive revertant was shown to have simultaneously regained both the ability to attach to neuraminidase-sensitive receptors on the tracheal ring respiratory epithelium in vitro and the ability to synthesize three virulent-strain-specific proteins which were not synthesized by the hemadsorption-negative mutant. Despite the persistence of the revertant in hamster lung tissue for 9 to 12 weeks postinfection, no cytopathology was observed. Intranasal inoculation of the revertant provided limited protection against a challenge dose of virulent M. pneumoniae.

Host discrimination of Mycoplasma pneumoniae proteinaceous immunogens

The immune response of experimentally infected hamsters and human patients to Mycoplasma pneumoniae was examined by radioimmunoprecipation in conjunction with gel electrophoresis and fluorography. Both intrinsically and extrinsically labeled mycoplasma proteins were coincubated with acute and convalescent sera in a radioimmunoprecipitation assay. Two M. pneumoniae proteins were selectively precipitated by convalescent sera. These predominant immunogens were trypsin-sensitive, antibody-accessible surface proteins that co-migrate on polyacrylamide gels with proteins P1 and P2, which were previously implicated by us as mediators of cytadsorption. Anti-M. pneumoniae antiserum did not precipitate radiolabeled antigens derived from Mycoplasma orale or Mycoplasma salivarium. These data indicate that M. pneumoniae infection stimulates a specific and highly targeted host antibody response to key proteinaceous immunogens.

Aspects of serum and sputum antibody in chronic airways obstruction

Immunoglobulin levels and precipitating antibody against a range of microbial antigens were measured in simultaneously collected serum and sputum samples from patients with chronic bronchitis (11), cystic fibrosis (9), bronchiectasis (9), and asthma (4). Sputum was prepared by dialysis and high-speed centrifugation methods. Results showed that it was possible to detect precipitating antibody in the sputum, and the rate was increased when both methods were used. A discrepancy was noted between the detection rate in the sputum and serum. This, combined with the lack of correlation between sputum and serum immunoglobulins, lack of relationship between bronchial inflammation and sputum immunoglobulins, and the lack of IgM in the sputum suggested that the antibody and immunoglobulin were locally produced. Sputum IgA (7S) in patients with chronic bronchitis was significantly lower (P less than 0-05) than that found in patients with cystic fibrosis and bronchiectasis. Significant differences (P less than 0-05) were also noted in serum IgG levels between patients with chronic bronchitis, bronchiectasis, and cystic fibrosis while serum IgM levels in patients with chronic bronchitis were significantly lower (P less than 0-05) when compared to serum levels in patients with cystic fibrosis. The presence of precipitating antibody in the sputum raises the possibility that type III reactions may be important in the pathogenesis of these conditions.

Hospital treatment and diagnosis of Mycoplasma pneumoniae pneumonia

A study was started in 1972 in order to determine the true etiology of patients who presented with obscure pulmonary infiltrates. Patients who were included in this study had sera drawn on two occasions. Complete testing was performed for the various viruses and also for Mycoplasma pneumoniae antibodies. The study continued through 1975 and a total of 159 patients were included. Of these 159 patients, 28 had positive complement fixation tests for M. pneumoniae antibodies. The clinical profile and treatment course is outlined and discussed.

Opsonin-reversible resistance of Mycoplasma pneumoniae to in vitro phagocytosis by alveolar macrophages

Several species of mycoplasmas are responsible for respiratory disease in animals and man. As yet, little is known about the interaction of these pathogens with alveolar macrophages, one of the primary components of pulmonary resistance to infections. The present study was undertaken to develop an in vitro model to examine this organism-cell interaction, using a human pathogen, mycoplasma pneumoniae, and normal guinea pig alveolar macrophages. During a 24-h incubation of M. pneumoniae with a monolayer of macrophages, mycoplasmas were found to attach directly to the surface of the cells without inducing significant phagocytosis. Ultrastructurally, the organisms appeared bound to the cell membrane by their characteristic attachment organelles. Only after the addition of specific anti-mycoplasma serum were cells able to engulf attached and surrounding organisms. These data suggest that the interaction of M. pneumoniae and alveolar macrophages is a potentially important aspect of disease pathogenesis, and immune factors which might alter this interaction merit further examination.

In vitro response of human lymphocytes to Mycoplasma pneumoniae

In vitro culture and stimulation of human peripheral lymphocytes were employed to investigate the role of cellular immunity in Mycoplasma pneumoniae disease. Subjects with documented natural infections served as donors. The lymphocyte response to whole M. pneumoniae organisms was determined as incorporation of tritiated thymidine in a semimicro culture system. The range of cellular reactivity stimulated by specific antigen was within the range stimulated by phytohemagglutinin. The difference between responses of subjects with documented infection and serologically negative controls was highly significant. Specific reactivity of peripheral lymphocytes correlated closely with the presence of serum growth-inhibiting antibodies, and both persisted for several years following infection. Serum complement-fixing titers correlated well with lymphocyte stimulability during the first year but antibody, as measured by this technique, tended to disappear in later convalescence. In light of previous studies, which revealed a lack of correlation between humoral antibodies and resistance to reinfection, these results suggest that immunity to M. pneumoniae infection is mediated by circulating small lymphocytes.