Immune response in chlamydial conjunctivitis among neonates and adults with special reference to tear IgA

Mucosal defense of the outer eye

A combination of mechanical, anatomical, immunological, and microbiological factors prevent infection of the outer eye. Mechanical and anatomical factors include the intact epithelium of the conjunctiva and cornea and the constant blinking action of the eyelids. Tear components that play a role in eye defense include lysozyme, immunoglobulins, lactoferrin, and betalysin. The normal bacterial flora of the conjunctiva may also have an inhibitory effect on the survival of more pathogenic species. The eye is linked to the common mucosal immune system, thus gaining the benefits of a system of microbial defense which is primed in the gastrointestinal tract, where a continuing large antigen load is capable of stimulating ongoing immune protection. The relative roles of the various factors contributing to prevention of eye infection remain to be fully defined.

Detection of antichlamydial antibodies in tears: a diagnostic aid?

OBJECTIVES

The antibody response in sera and tears of 167 patients with suspected chlamydial conjunctivitis was compared with the antibody response in sera and tears of 45 patients with symptoms of urogenital chlamydial infection to discover whether and which type of antichlamydial antibody detected in tears may be of diagnostic help in chlamydial conjunctivitis.

METHODS

Diagnosis was based on chlamydial antigen detection from the conjunctiva and urogenital tract, done by a direct immunofluorescence assay, McCoy cell culture, and polymerase chain reaction. Additionally, antichlamydial immunoglobulin A (IgA) and immunoglobulin G (IgG) were determined in sera and tears of all patients by an immunoperoxidase assay.

RESULTS

Two hundred twelve patients were examined--167 with conjunctivitis, 45 with symptoms of urogenital chlamydial infection. Cell culture, direct immunofluorescence assay, and polymerase chain reaction brought identical results. Conjunctival specimens taken from 33 (20%) of the patients with conjunctivitis were Chlamydia antigen positive; specimens taken from 134 (80%) were negative. Antichlamydial antibodies were found in tears of 29 (88%) of the patients with conjunctivitis whose specimens were Chlamydia antigen positive. Fifty-four (40%) of the patients with conjunctivitis whose specimens were Chlamydia antigen negative had antichlamydial antibodies in their tears. Twenty-five patients with urethritis (56%) were Chlamydia antigen positive in urethral swabs; 20 (44%) were negative. Antichlamydial antibodies were found in the tears of eight (32%) of the Chlamydia antigen-positive and two (10%) of the Chlamydia antigen-negative patients with urethritis. In contrast to patients with conjunctivitis, findings for patients with urethritis always were negative for antichlamydial IgG in the tears.

CONCLUSION

Antichlamydial antibodies in tears were seen significantly more often in patients with conjunctivitis than in those with urethritis (P < or = 0.05). Antichlamydial IgG was found only in tears of patients with conjunctivitis. Therefore, the authors conclude that the detection of antichlamydial IgG in the tears might be helpful for diagnosis in patients with suspected chlamydial conjunctivitis who have antigen-negative conjunctival swabs.

Measurement of sputum antibodies in the diagnosis of acute and chronic respiratory infections associated with Chlamydia pneumoniae

The aim of this study was to develop methods for the measurement of sputum antibodies in the laboratory diagnosis of acute and chronic lower respiratory tract infections caused by Chlamydia pneumoniae. Paired serum specimens, sputum specimens, and pharyngeal or nasopharyngeal swabs were obtained from 97 patients; 51 of them had community-acquired pneumonia, and 46 had chronic obstructive pulmonary disease (COPD). C. pneumoniae-specific serum immunoglobulin G (IgG), IgA, and IgM antibodies were measured by the microimmunofluorescence (micro-IF) test. For sputa, specific IgA and IgG antibodies were measured by the micro-IF test and secretory IgA (sIgA) was measured by enzyme immune assay (EIA) with C. pneumoniae elementary bodies as the antigen. Sputum IgA and sIgA antibodies to C. pneumoniae were found, respectively, in 52 and 51% of the COPD patients. Elevated levels of stable serum IgG and IgA antibodies (IgG titer of > or = 128 and IgA titer of > or = 40), suggesting chronic infection, were found in 54% of the COPD patients. The sensitivity for the sputum IgA micro-IF test compared with elevated serum antibody levels was 87.5%, and that for the sputum sIgA EIA was 88%; the respective specificities were 90 and 95%. Acute C. pneumoniae infection was diagnosed in seven pneumonia patients, and two (29%) of these patients were positive by sputum EIA antibody measurements. Two pneumonia patients without acute infection had stable elevated IgG and IgA levels in their sera, and both of them were sputum antibody positive. We conclude that the measurement of IgA antibodies to C. pneumonia in sputum is a useful additional diagnostic tool for chronic C. pneumoniae infections.

Chlamydial etiology of acute lower respiratory tract infections in children in the Sudan

The role of Chlamydia pneumoniae in 110 Sudanese children with signs of acute lower respiratory tract infections (ALRI) was investigated. Four (3.6%) had evidence of C. pneumoniae infection, of whom 3 were culture-positive, while 1 had an antibody response suggesting a recent infection. IgG antibodies at a titer of > or = 1:32 to C. pneumoniae, Chlamydia psittaci and Chlamydia trachomatis were detected in 27 (24.5%), 27 (24.5%) and 7 (6.4%) of the 110 ALRI cases, respectively. C. pneumoniae, C. trachomatis or C. psittaci were not detected in nasopharyngeal secretions from any of 110 patients when fluorescence-labeled specific monoclonal antibodies were used. In a seroepidemiological survey, 318 healthy Sudanese persons aged between 1 month and 67 years were studied for C. pneumoniae antibodies.

Antichlamydial activity of lacrimal fluid in patients with trachoma

The effect of lacrimal fluid on the growth of Chlamydia trachomatis in cycloheximide-treated McCoy cells was studied in 172 persons with active trachoma (Group A), in 54 with scarring trachoma (Group B) and in 40 healthy subjects (Group C). The patients in groups A and B were treated with tetracycline eye ointment for 4-6 weeks after which tears were collected for retesting. Pooled lacrimal fluid from patients with active trachoma, collected before treatment, had a higher antichlamydial activity compared with healthy individuals. No reduction of the chlamydial inclusion count was seen with such fluid from patients with scarring trachoma. After tetracycline treatment, patients with active trachoma had a slight decrease in their inhibitory activity. In patients with scarring trachoma, the treatment did not significantly reduce the inclusion count. Antichlamydial antibodies were detected more often in patients with active trachoma than in patients with scarring trachoma, while the healthy individuals had no such antibodies. Ultrafiltered and nonfiltered lacrimal fluids were equally effective in inhibiting C. trachomatis inclusion-formation. The inhibitory principle had a molecular weight of less than 10,000 Da.