Effect of cyclosporine A on the corneal inflammatory response in herpes simplex virus keratitis.

The effects of cyclosporine A (CyA), a selective inhibitor of T-lymphocyte function, on the corneal inflammatory response in herpes simplex virus (HSV) stromal keratitis was followed during the course of experimental HSV keratitis in the rabbit. The corneal response, characterized by polymorphonuclear leukocytes (PMN) and mononuclear cells, is an immunologically specific event that is dependent on the presence of viral antigens and immune cells. CyA treatment during the course of HSV keratitis resulted in a more severe and persistent stromal disease and more anterior chamber involvement than that seen in the solvent control-treated HSV-infected animals. Clinical observations correlated well with histological studies which confirmed a greater incidence of mononuclear and PMN infiltrates throughout the anterior chamber and stroma in the CyA-treated animals. HSV antigens were present in the corneas from both infected groups as observed by immunofluorescence staining, but endothelial localization of HSV antigens was seen primarily in the CyA-treated animals, often accompanied by cells in the anterior chamber. No significant differences in IgG and IgM staining in the diseased corneas and anterior chamber were noted between the CyA-treated and solvent control groups which suggests that there was no local B-cell immunosuppression.

Effects of cyclosporine A on clinical and immunological parameters in herpes simplex keratitis.

The immunosuppressive effects of cyclosporine A (CyA) on the clinical and antiviral immune responses were examined in experimental herpes simplex virus (HSV) keratitis in the rabbit in order to clarify the role that immune lymphocytes play in herpetic stromal disease. Cyclosporine A was administered intramuscularly to rabbits daily starting from the time of corneal infection with HSV until day 14 postinfection. Control HSV-infected rabbits received daily injections of the solvent vehicle alone. HSV-infected rabbits receiving CyA treatment showed more severe and persistent stromal keratitis, and a greater incidence and duration of virus recovery from the cornea. Suppression of cellular immune responses to T cell mitogens, B cell mitogens (anti-rabbit immunoglobulins), and HSV antigens were observed in the CyA treatment group. These results show that in CyA-treated HSV-infected rabbits the antiviral immune responses are inhibited. Acute viral infections with cytopathic viruses such as HSV may therefore be more dramatic, suggesting that CyA may facilitate the potentiation of HSV infections ordinarily suppressed by immune cells.

Experimental herpesvirus keratitis in the rabbit: topical versus intrastromal infection routes.

Intrastromal and topical routes of infection of rabbit corneas with the HF strain of herpes simplex virus type 1 were compared clinically to determine which route of infection would present the best model of disciform edema and of deep stromal keratitis for our further studies on how the immune response of the infected animals may influence the expression of clinical disease. In addition, virus clearing and persistence of viral antigens as immunologic stimuli were monitored by virologic and electron microscopic immunocytochemical studies. We found topical infection to be preferable to the intrastromal infection route for presenting stromal disease in that it resulted in a higher incidence of epithelial disease with less anterior chamber involvement. The topical infection route model should be valuable in studies of cell-mediated immune response against HSV-infected cells.

Immunopathogenesis of corneal inflammation in herpes simplex virus stromal keratitis: role of the polymorphonuclear leukocyte.

The present studies suggest that polymorphonuclear leukocytes (PMNs) play an essential role in the development of corneal infiltrates in stromal herpes virus (HSV) keratitis. Corneal infiltration was seen rarely in herpes-infected animals treated with anti-PMN serum or with chemotherapy to reduce the numbers of circulating PMNs. By contrast, at least two thirds of the control animals with intact PMNs and infected with herpes virus developed stromal infiltrates. Host complement was localized with HSV antigen and rabbit gamma globulin along with inflammatory cells in the corneas of animals with stromal infiltrates. In the absence of PMN infiltrates, neither complement nor a significant amount of gamma globulin was localized in the corneal stroma. In the PMN-depleted animals, only viral antigen was detected in the stromal keratocytes.

Humoral and cell-mediated immune responses to epidermal growth factor in the rabbit.

Epidermal growth factor (EGF), which has been shown to stimulate epidermal proliferation and keratinization and to induce regeneration of rabbit corneal epithelium, was studied for its immunogenic potential in rabbits. Mouse-derived EGF was administered topically, subconjunctivally, intrastromally, and systemically. Systemic immunization was done both with and without complete Freund's adjuvant (CFA). EGF-stimulated cultures of lymphocytes from peripheral blood, spleen, and lymph nodes of all immunized animals were tested for cell-mediated immunity (CMI) to EGF. All experimental animals demonstrated CMI as determined by either classic positive delayed skin tests or by in vitro production of migration inhibitory factors, regardless of the route of sensitization. Only animals immunized systemically with EGF and CFA produced high-titered specific anti-EGF antibody, and only this group showed ocular reactions after subsequent topical challenge of EGF. These results suggest that antibody to EGF is the major cause for ocular inflammatory reactions observed subsequent to topical EGF challenge of a sensitized animal.

Induction of cell-mediated immunity in herpes simplex virus keratitis. Kinetics of lymphocyte transformation and the effect of antiviral antibody.

The in vitro lymphoproliferative responses to herpes simplex virus (HSV) antigens were followed in rabbits with herpesvirus infection of the cornea. The proliferative cellular responses occurred early in infection and were demonstrated by lymphoid cells from the local lymph nodes at day 5, the peripheral blood at day 11, and the spleen after day 14. The presence of autologous serum antibodies suppressed lymphoproliferative responses of the lymph node lymphocytes to HSV antigens early in infection at day 5, the time at which antibody production is first noted. Peripheral blood and spleen cells were not appreciably influenced at early time periods. However at 7 months after infection, the presence of autologous serum antibodies stimulated spleen lymphocytes from animals with recurrent disease. These results indicate that antiviral antibodies can affect the cellular immune response in herpesvirus infections by modulating the lymphoproliferative response to herpes antigens.

Rapid detection of experimental E. coli endophthalmitis by the Limulus lysate test.

Experimental E. coli endophthalmitis was produced in rabbits. The Limulus lysate test was applied to aqueous and vitreous samples at various intervals after the intravitreal injection of E. coli organisms. Results indicated that this test is feasible using vitreous and aqueous samples. The Limulus test was positive for E. coli endotoxin within hours after infection, requiring only 1 hr to determine the presence of endotoxin after sampling. This test may have some value in the rapid diagnosis of gram-negative endophthalmitis.

Immunology of herpesvirus infection: immunity to herpes simplex virus in eye infections.

A gereral, overall pattern of the temporal relationship and interaction between cell and antibody-mediated immune responses following herpes simplex virus infection of the rabbit cornea can be synthesized from our studies. Cell-mediated immunity (CMI) appears early following infection, at a time when mononuclear and lymphocytic cellular proliferation occur at the limbus. Interaction between specifically immune lymphocytes with virus antigens are detected by lymphocyte blastogenesis and migration inhabiting factor. During stromal keratitis, a second phase of CMI involves transient virus-specific cytotoxic lymphocytes, which destroy cells that display viral-induced antigens on their surface. Chemotatic factors generated by viral antigens alone or with antiviral antibody or by virus-sensitized lymphocytes play a role in attracting polymorphonuclear leukocytes to the cornea during stromal keratitis. Soluble mediators of CMI secreated by activated lymphocytes act both specifically and nonspecifically on virus-infected cells, allowing cell destruction and making intracellular virus available for neutralization by antiviral antibody. Cell-mediated immunity in the acute infection, diminishes with the appearance of significant antiviral antibody titers. The late phase of the corneal immune response results from a local antigen-antibody interaction and is characterized by cells predominantly of the plasmacytic type. The presence of complement-dependent cytotoxic antibodies capable of destroying virus-infected cells provide an additional factor in restriction of infection.

Comparison of methods for coccidioidomycosis complement fixation.

A Laboratory Branch Task Force of the National Communicable Disease Center has proposed a standardized complement fixation procedure (LBCF) and an adaptation of this to microtitration techniques (MT) as uniform methods for performing complement fixation (CF) tests. A common procedure should make CF results from one laboratory more comparable to another. In addition, it would be preferable if the common procedure reproduced the titer levels of a testing procedure which is to be replaced, particularly when valid clinical interpretations have been derived from the latter. Replicated sets of sera were tested by the LBCF, MT, and the standard Smith CF procedure for coccidioidomycosis. Results with all three procedures were highly reproducible within an acceptable one-tube variation of a twofold dilution series, but the frequency of one-tube variations was greater with the MT method than with the other two. There was no statistical difference in the titers obtained with the Smith and LBCF procedures, but there was a significant difference when the MT results were compared to those with the Smith method. The LBCF method should be acceptable as a standardized and uniform CF procedure for coccidioidomycosis, subject to comparative testing between different laboratories.