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Published on: September 20, 2010
Immunopathology of chronic experimental histoplasmic choroiditis in the primate
A Anderson1, W Clifford, I Palvolgyi
1Doheny Eye Institute, Los Angeles, CA 90033.
Insights
Researchers developed a nonhuman primate model for ocular histoplasmosis to study choroidal inflammation. Chronic lesions differ based on B-lymphocyte presence, indicating distinct immunopathologies in experimental histoplasmic choroiditis.
Area of Science:
- Ophthalmology
- Immunology
- Infectious Diseases
Background:
- Ocular histoplasmosis is a fungal infection causing vision-threatening inflammation.
- Understanding the immune response in the choroid is crucial for managing this condition.
Purpose of the Study:
- To characterize the cellular immunopathology of acute and chronic experimental ocular histoplasmosis.
- To differentiate between distinct types of chronic inflammatory lesions.
Main Methods:
- Development of a nonhuman primate model for ocular histoplasmosis.
- Utilized anti-human monoclonal antibodies to identify and quantify inflammatory cell subsets.
- Compared cellular infiltrates in acute (<65 days) and chronic (>1 year) choroidal lesions.
Main Results:
- Identified immunopathologically distinct chronic lesions based on the presence of dense lymphocytic foci.
- Chronic lesions with B-cell foci showed significantly higher percentages of mature B-cells and helper-inducer T-cells.
- Lesions with B-cell foci exhibited a higher mean helper-suppressor T-cell ratio.
Conclusions:
- The nonhuman primate model effectively elucidates choroidal immunopathology in ocular histoplasmosis.
- Chronic lesions in ocular histoplasmosis can exhibit distinct immune profiles, influenced by B-cell infiltration.
- These findings suggest varying immunopotentials among chronic histoplasmic choroidal lesions, even within the same eye.
Abstract:
A nonhuman primate model of ocular histoplasmosis was developed that enabled the authors to define the choroidal cellular immunopathology of both the acute and chronic phases of experimental histoplasmic choroiditis. Anti-human monoclonal antibodies were used to identify the inflammatory cell subsets and to calculate their relative percentages in the choroidal inflammatory lesions. Comparison of the acute (less than or equal to 65 days) and chronic (greater than or equal to 1 yr) phases suggested possible variations in the evolution of these lesions, resulting in the development of immunopathologically distinct chronic lesions. In this model, these late lesions could be differentiated by the presence or absence of dense lymphocytic foci, comprised predominantly of mature B-lymphocytes, located within the more diffuse inflammatory cell background. The chronic lesions containing these B-cell foci had significantly higher percentages of both mature B-cells (P less than 0.0001) and helper-inducer T-cells (P less than 0.05) than did the chronic lesions without B-cell foci. The increase in helper-inducer T-cells in the chronic lesions with B-cell foci resulted in a higher mean helper-suppressor T-cell ratio (mu = 0.60) than that seen in lesions lacking foci (mu = 0.33). These findings suggest that, even in the same eye, individual chronic histoplasmic choroidal lesions, which clinically resemble "histo spots" in humans, may have different immunopotentials.
