{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T12:48:41Z","timestamp":1790254121583,"version":"4.1.0"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"10","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1996,5,14]]},"abstract":"<jats:p>Little is known about the mechanisms involved in human gammadelta T-cell tolerance to self or to foreign antigens. Patients with congenital toxoplasmosis offer a unique opportunity to examine Vdelta2+ gammadelta T-cell tolerance. Analysis of gammadelta T cells in patients with congenital toxoplasmosis revealed evidence for anergy of these cells with or without clonal Vdelta2+ gammadelta T-cell expansion in the acute phase of the Toxoplasma infection. T cells in general were unresponsive and did not proliferate upon exposure to mitogens or to Toxoplasma lysate antigens or in response to live Toxoplasma-infected cells when the congenitally infected infants were 1 month of age, and they exhibited selective anergy to Toxoplasma lysate antigens and live Toxoplasma-infected cells when the infants were aged 5 months. During the chronic phase of congenital toxoplasmosis in the patients who were more than I year of age, the repertoires of the gammadelta T-cell receptors were found to be within normal ranges. In addition, in the chronic phase, the gammadelta T cells proliferated and secreted gamma-interferon in response to exposure to live Toxoplasmia-infected cells. By contrast, alphabeta T cells remained anergic. Vdelta2+ gammadelta T cells have been considered to undergo extrathymic maturation and thus to be subject to development of peripheral tolerance. Our findings indicate that Vdelta2+ gammadelta T-cell tolerance was lost in these infected infants earlier than alphabeta T-cell tolerance. These findings suggest that gammadelta T cells play a role in protection against Toxoplasma gondii in the chronic phase when congenitally infected children are more than 1 year of age, especially in those in whom alphabeta T cells continue to exhibit deficits in specific immune responses to Toxoplasma antigens.<\/jats:p>","DOI":"10.1073\/pnas.93.10.5136","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T10:34:16Z","timestamp":1027679656000},"page":"5136-5140","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":35,"title":["Human V delta 2+ gamma delta T-cell tolerance to foreign antigens of Toxoplasma gondii."],"prefix":"10.1073","volume":"93","author":[{"given":"T","family":"Hara","sequence":"first","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S","family":"Ohashi","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Y","family":"Yamashita","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"T","family":"Abe","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H","family":"Hisaeda","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K","family":"Himeno","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R A","family":"Good","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K","family":"Takeshita","sequence":"additional","affiliation":[{"name":"Department of Child Neurology, Institute of Neurological Sciences, Tottori University School of Medicine, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1996,5,14]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.93.10.5136","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T14:09:54Z","timestamp":1649858994000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.93.10.5136"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1996,5,14]]},"references-count":0,"journal-issue":{"issue":"10","published-print":{"date-parts":[[1996,5,14]]}},"alternative-id":["10.1073\/pnas.93.10.5136"],"URL":"https:\/\/doi.org\/10.1073\/pnas.93.10.5136","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1996,5,14]]},"assertion":[{"value":"1996-05-14","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}