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C. Miyamoto, R. N. Belfort, S. DiCesare, R. Belfort, Jr., P. Logan, M. N. Burnier, Jr.; The Use of CD-25 as an Immunohistochemical Marker for Acquired Ocular Toxoplasmosis. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3896.
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Toxoplasmosis is the most common cause of posterior infectious uveitis worldwide. It is often impossible to determine the congenital or acquired nature of this particular uveitic process. Interleukin-2 in peripheral blood has been described as a possible marker for acquired toxoplasmosis. The purpose of this study is to evaluate the histopathological characteristics of congenital and acquired toxoplasmosis using CD-25 as a marker for the expression of interleukin-2 (IL-2).
Ten formalin-fixed, paraffin-embedded enucleated globes from ten immunocompetent patients with clinical diagnosis of toxoplasmosis were evaluated. Four patients had the acquired form of ocular toxoplasmosis (positive IgG and IgM) while six had been diagnosed as congenital toxoplasmosis (positive IgG and negative IgM). Histopathological slides were reviewed for the extension of the retinal necrosis, number of toxo cysts, the granulomatous reaction and the presence of T and B cells within the choroid, as well as the IL-2 expression. In order to perform this evaluation, immunohistochemistry using monoclonal antibodies to observe the expression of CD20, CD4, CD8, CD68 and CD25 was done.
The histopathological evaluation disclosed no differences between acquired and congenital ocular toxoplasmosis regarding the extension of retinal necrosis and the number of toxo cysts. The granulomatous choroiditis as well as the presence of T and B-lymphocytes were similar in all cases including acquired and congenital disease. However, CD-25 showed a higher expression of IL-2 on the 4 acquired cases of ocular toxoplasmosis compared to the congenital ones. Based on the expression of CD-25, two of the previously categorized as congenital cases were reclassified as acquired toxoplasmosis.
The extension of the retinal necrosis, number of toxo cysts, and the severity of the granulomatous choroiditis were similar in both acquired and congenital cases. High expression of CD-25 was found exclusively in acquired cases of ocular toxoplasmosis. To the best of our knowledge, this is the first report showing that the use of CD-25 as a marker for interleukin-2 is helpful to differentiate between acquired and congenital ocular toxoplasmosis.
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