Chlamydiae and polymorphonuclear leukocytes: unlikely allies in the spread of chlamydial infection.

While much is known about the attachment of the chlamydiae to the host cell and intracellular events during the developmental cycle, little is known about the mechanism(s) by which elementary bodies exit the cell. In this report, we use the guinea-pig conjunctival model of Chlamydia caviae infection to present in vivo ultrastructural evidence supporting two mechanisms for release of chlamydiae from the mucosal epithelia. Four days after infection, histopathologic observation shows an intense infiltration of polymorphonuclear leukocytes (PMN) in the conjunctival epithelium. Using transmission electron microscopy, a gradient-directed PMN response to chlamydiae-infected epithelial cells was observed. As PMN infiltration intensifies, epithelial hemidesmosome/integrin/focal adhesion adherence with the basal lamina is disconnected and PMNs literally lift off and release infected superficial epithelia from the mucosa. Many of these infected cells appear to be healthy with intact microvilli, nuclei, and mitochondria. While lysis of some infected cells occurs with release of chlamydiae into the extracellular surface milieu, the majority of infected cells are pushed off the epithelium. We propose that PMNs play an active role in detaching infected cells from the epithelium and that these infected cells eventually die releasing organisms but, in the process, move to new tissue sites via fluid dynamics.

Chlamydia trachomatis infection in infant delivered by cesarean section.

Neonatal Chlamydia trachomatis infection is thought to be acquired as a result of contact with infected cervical secretions during vaginal delivery. An infant, delivered by cesarean section, who was infected with C trachomatis has been described. At 31 days of age he had conjunctivitis and respiratory distress. Nasopharyngeal aspirate grew C trachomatis and serum IgM antibody titer was 1:32 for serotype J. The patient's mother had serum IgG antibody against C trachomatis serotype J. Her cervical culture was negative for Chlamydia; however, cultures were not taken until two months after delivery and she had received antibiotics for postpartum fever and abdominal pain. The literature has been reviewed and possible modes of transmission have been discussed.

Resistance to reinfection with a chlamydial agent (guinea pig inclusion conjunctivitis agent).

Although most chlamydial infections are chronic or recurrent, infection of the guinea pig's eye with guinea pig inclusion conjunctivitis (GPIC) agent induces a marked resistance to reinfection. To characterize this resistance to GPIC agent, we compared the disease and infection in previously infected guinea pigs with that in animals infected for the first time. In animals experiencing primary infection, even the lowest dose (10 egg-lethal doses [ELD50]) produced the disease and chlamydial inclusions in conjunctival smears, but the incubation period became progressively shorter with the highest inocula (10(4) and 10(5) ELD50). In animals with previous infection only these two highest inocula produced disease and infection, but the disease was short-lived, and replication of the agent was severely limited. The mechanism of this resistance may be due to secretory antibody in the tears, cellular immunity, or other local factors.

Immune mechanisms in chlamydial eye infection. Development of T suppressor cells.

In vitro proliferation assays of whole peripheral blood mononuclear leukocytes (PBML) and PBML depleted of suppressor T cells were performed in cynomolgus monkeys after they had received one, two, or repeated ocular inoculations with Chlamydia trachomatis. Whole PBML responded only weakly to chlamydial antigen, and responses to concanavalin A were depressed for 12 wk following ocular infection. Depletion of the suppressor T cell population did not result in increased chlamydia-specific proliferation until 14-20 wk after initial antigen contact, suggesting that circulating suppressor T cells are not responsible for the initiation of the chronic state.

Oral immunization against chlamydial eye infection.

The effects of enteric administration of different preparations of Chlamydia trachomatis prior to ocular challenge with live chlamydia were compared to the immunity that develops after recovery from ocular infection. Oral immunization with either live homologous serovar B or with formalin-killed heterologus serovar L2 did not influence the response to subsequent ocular challenge. Although oral immunization with live serovar led to protection against heterologous ocular challenge with serovar B, oral immunization with noninfectious UV-irradiated serovar L2 led to more severe and prolonged disease. An immunizing regimen designed for maximal mucosal and systemic immunity also resulted in protection against homologous ocular challenge. Although protection was correlated with the presence of serum IgA antibodies, no clear mechanism for the protective ocular immunity to chlamydial infection has emerged. These studies show that it is possible to stimulate mucosal immunity to induce protection against subsequent ocular challenge with C. trachomatis that is equal to that which follows prior ocular infection.

Serum and tear antibodies to Chlamydia after reinfection with guinea pig inclusion conjunctivitis agent.

Repeated inoculation of th eyes of guinea pigs with the naturally occurring Chlamydia psittaci agent, guinea pig inclusion conjunctivitis (GPIC), showed that animals gradually become susceptible to reinfection with the passage of time after primary infection. Higher levels of serum IgG antibody had a significant association with resistance to challenge inoculation only with a high dose (250 ELD50) but not with a low dose (25 ELD50) inoculum. With each inoculum, however, some animals with high serum antibody were susceptible. the presence of antibodies in tears did not correlate with resistance to the first low-dose challenge inoculation, but both tear IgG and secretory antibody did have a significant association with resistance on the second rechallenge with a high-dose inoculum. Topical treatment of the eye with immune serum or tears during primary infection reduced the amount of agent in the conjunctiva only during the period of application. Local treatment of the eye with heat-killed vaccine prior to primary infection did not produce detectable antibody or protect animals against challenge inoculation; this local immunization did "prime" the animals, however, so that they had an accelerated antibody response after infection. Although there is abundant evidence that local immunity has an important role in resistance to challenge inoculation with GPIC, serum and tear antibody levels correlate equally well with resistance to repeated ocular challenge inoculation. Effective immunization procedures for this chlamydial infection then would involve stimulation of both local and systemic immune responses.

Murine model of ocular infection by a human biovar of Chlamydia trachomatis.

PURPOSE: A human biovar of Chlamydia trachomatis was used to develop a murine model of ocular chlamydial infection. The inbred mouse model will allow detailed immunologic studies during ocular infection, and use of a human biovar for infection may aid in identification of appropriate vaccine strategies against chlamydial infections. METHODS: BALB/c, C3H/HeN, and C57B1/6J mice (n = 5 to 10 mice/group) were topically infected in the conjunctiva with C serovar of C. trachomatis. The effects were tested of single and repeated infection with 5000 inclusion-forming units (IFU) in 5 microliters and different inoculum doses. Conjunctival surfaces of both eyes were swabbed for microbiologic signs (isolation culture or direct fluorescent antibody staining) of infection over 4 to 6 weeks. Conjunctivae were removed for histopathologic study, and lymphocytes from draining cervical lymph nodes and spleens were tested for chlamydia-specific proliferative responses. Serum was obtained from all mice and tested for anti-chlamydial antibodies. RESULTS: BALB/c and C3H/HeN mice developed dose-dependent microbiologic, histopathologic, and immunologic evidence of ocular infection. Eyes of mice were culture-positive from day 7 through at least day 21, with the peak of infection at days 10 to 14 after infection. Histopathologically, the development of conjunctival subepithelial mononuclear infiltration, exudate, and loss of goblet cells occurred within 1 week. Dose-dependent lymphoproliferative responses to whole chlamydial elementary bodies were observed; anti-chlamydial antibody was detected by immunoblotting only in infected mice. CONCLUSIONS: Several strains of inbred mice are susceptible to human chlamydial biovars and may provide a useful alternative disease model in which to study the immunopathogenesis of ocular chlamydial infection and test of vaccine candidates derived from clinically relevant human biovars.

Systemic immunization with Hsp60 alters the development of chlamydial ocular disease.

PURPOSE: To determine whether immunization with recombinant Hsp60 would exacerbate ocular pathology on challenge with viable chlamydial elementary bodies. METHODS: Guinea pigs were immunized either subcutaneously with recombinant Hsp60 or both subcutaneously with recombinant Hsp60 and ocularly with attenuated Salmonella typhimurium expressing the guinea pig inclusion conjunctivitis (GPIC) Hsp60 antigen. All animals were challenged in the conjunctiva with the agent of GPIC, and the degree of gross ocular pathology was determined. Immunoglobulin G (IgG) and immunoglobulin A (IgA) antibody titers to Hsp60 were measured in ocular secretions as a measure of the degree of immunization. RESULTS: In primary and challenge GPIC infection, the degree of gross ocular pathology was lower in the immunized group. The presence of high IgA and IgG antibody titers to Hsp60 in tears suggested that the response may have been modified by the presence of blocking antibodies that either may have removed the antigen quickly or prevented interaction with sensitized T cells. In contrast to subcutaneous immunization, the combined immunization regimen, consisting of subcutaneous recombinant Hsp60 followed by ocular inoculation of the attenuated Salmonella, resulted in no difference in gross pathology after reinfection of guinea pigs with GPIC. CONCLUSIONS: These data indicated that the immunization with Hsp60 did not produce exacerbated disease on challenge with viable organisms; however, the data suggested that the route of administration, form of antigen, or both may be critical in the disease process.

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

Tear and serum samples from 128 neonates and 122 adults with conjunctivitis were examined for antibodies to Chlamydia trachomatis with a micro-immunofluorescence (MIF) technique and the results compared to antigen detection by culture, enzyme immunoassay (EIA) (Chlamydiazyme, Abbott) and direct immunofluorescence (IF) (MicroTrak, Syva and Chlamyset, Orion) tests. From the 52 culture-positive adults, chlamydial IgA (titre greater than or equal to 1:8) antibodies were detected in 81% of the tear and in 62% of the serum samples, while 88% had such serum IgG antibodies (titre greater than or equal to 1:32). The persistence of chlamydial IgA in tears and sera was related to the duration of symptoms of conjunctivitis and the antibody titres declined after institution of antibiotic treatment. In the adults, the sensitivity of the MIF tear IgA antibody test (81%) was higher than that of the EIA (71%) and the IF (MicroTrak 71% and Chlamyset 62%) tests. The specificity for the MIF test was 79%, while it was 100% for the EIA and the two IF tests. Of the 67 chlamydia-infected neonates, 36% had chlamydial tear IgA antibodies, while such antibodies were only found in 15% of the sera. No neonates with chlamydia-negative conjunctivitis had chlamydial IgA antibodies. The MIF test may be used as a diagnostic method complementary to culture, EIA and IF tests in the diagnosis of chlamydial conjunctivitis in adults, but is not applicable in neonates.

Development of chronic conjunctivitis with scarring and pannus, resembling trachoma, in guinea-pigs.

Guinea-pigs were repeatedly infected with guinea-pig inclusion conjunctivitis agent. Reinfection caused severe conjunctival inflammation, and repeated reinfection led to chronic inflammation lasting for many months. This was followed by the development of pannus, follicles on the palpebral conjunctivae, scarring of the lower palpebral conjunctiva, and deformities of the lower lid. Reinfection was accompanied by small numbers of inclusion-bearing cells, small numbers of polymorphonuclear cells, and high numbers of mononuclear cells. There was no increase in the level of serum antibodies. The chronic conjunctivitis was associated with high numbers of mononuclear cells and no inclusions or polymorphonuclear cells. The response to reinfection appears to be a delayed-type hypersensitivity reaction, and we suggest that the chronic inflammation, pannus, scarring, and lid deformities associated with hyperendemic trachoma may be due to repeated reinfection combined with delayed-type hypersensitivity.

Prevalence of Chlamydia trachomatis pooled serotypes BDE and FGK in children with chronic follicular conjunctivitis.

PURPOSE: To evaluate type-specific antichlamydial antibody IgG in children with chronic follicular conjunctivitis. METHODS: A total of 90 serum samples from juvenile patients with chronic follicular conjunctivitis were collected in the Southeastern Anatolian region of Turkey where trachoma is still endemic. These samples were investigated regarding Chlamydia trachomatis pooled serotype-specific IgG by using the micro-immunofluorescence test. A titer of 1/32 or higher was considered positive. RESULTS: Specific IgG seropositivity to Chlamydia trachomatis titer was found in 33 (36.1%) of the 90 subjects. A higher titer was observed frequently in the serotypes pooled in BDE (21 subjects), CHIJ (10 subjects), and FGK (2 subjects), respectively. CONCLUSIONS: The presence of antichlamydial antibodies in blood should always be interpreted in accordance with the history of the patient, the clinical picture, and the course of the disease. In the diagnosis of Chlamydia trachomatis infections in a patient with chronic follicular conjunctivitis, not only genus-specific antibodies but also the presence of the subspeciespecific antibodies should be investigated.

Guineapig inclusion conjunctivitis (GPIC) in a commercial colony.

Serological findings in a commercial colony of Hartley guineapigs revealed that about 70% had antibodies to Chlamydia psittaci as detected by the microimmunofluorescence method. Conjunctivitis was evident in 14% of 86 guineapigs examined. Chlamydial antigen was detected in conjunctival scrapings by a direct immunofluorescence test using Chlamydia-specific monoclonal antibody; however, C. psittaci was not demonstrated by other methods.

[Study of serological diagnosis in ocular chlamydial infection with IPAZYME].

We employed a indirect immunoperoxidase assay (IPAZYME in the evaluation of IgG and IgA antibody for Chlamydia trachomatis in serum samples from 218 patients such as cicatricial trachoma 55 cases, culture-positive adult inclusion conjunctivitis 48 cases and culture-negative conjunctivitis 47 cases, aged people, 68 cases as controls respectively. Frequency of positive IgG antibody showed a significant difference between adult inclusion conjunctivitis or cicatricial trachoma and controls. IgA antibody was positive in 25/48 (52%) in adult inclusion conjunctivitis and in 7/55 (12%) in cicatricial trachoma cases. Serum IgA antibody against Chlamydia trachomatis is of value to be an index of active ocular chlamydial inflammation. The correlation between severity of conjunctival cicatrix or corneal punnus and titers of IgG antibody was also significant.