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Bob Meek, Vincent N. A. Klaren, Nico J. van Haeringen, Aize Kijlstra, Ron Peek; IgA Antibodies to Toxoplasma gondii in Human Tears. Invest. Ophthalmol. Vis. Sci. 2000;41(9):2584-2590.
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purpose. To investigate whether mucosal immune responses directed against the
ubiquitous parasite Toxoplasma gondii can be detected in
tears of healthy humans.
methods. Nonstimulated tears and blood were obtained from 62 healthy humans
(mean age, 35 ± 10 [SD] years). Serum anti-T. gondii immunoglobulin titers were determined by Sabin–Feldman (SF) dye test.
Western blot analysis was used to compare the anti-T. gondii repertoire in tears and serum, and antibody avidity was determined by
urea elution. Diluted tear and serum samples were incubated with the
intact parasite to determine whether the antibodies found in tears and
serum are capable of binding to surface exposed antigens of T.
results. Eighty-one percent of the individuals tested had an anti-T.
gondii IgA response in their tears, whereas only 23% had evidence
of systemic immunity against the parasite. There was no apparent
relation between chronic infection and presence of anti-T.
gondii IgA in tears. Characteristically, the antigens recognized
by the IgA antibodies in tears were often limited to at least one of
four antigens with molecular weights of 74, 70, 49, and 34 kDa. The
avidity of the anti-T. gondii IgA antibodies in tears was
similar to the avidity of serum IgG antibodies. IgA antibodies directed
against the 49- and 74-kDa antigens recognized epitopes exposed on the
surface of the parasite.
conclusions. A major finding of this study is that tears of many individuals,
chronically infected or not, contain IgA antibodies against T.
gondii. It is not known whether these frequently observed antibody
responses are the result of common mucosal immune responses against T. gondii or represent the natural antibody
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