{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T07:04:41Z","timestamp":1791097481379,"version":"4.1.0"},"reference-count":42,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2003,8,1]],"date-time":"2003-08-01T00:00:00Z","timestamp":1059696000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2003,8,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Both CD4+ T cells and B cells are critical for defense against Pneumocystis carinii infection; however, the mechanism by which B cells mediate protection is unknown. We show that P. carinii-specific IgM is not sufficient to mediate clearance of P. carinii from the lungs since CD40-deficient mice produced normal levels of specific IgM, but were unable to clear the organisms. Using chimeric mice in which the B cells were deficient in CD40 (CD40KO chimeras) we found that clearance of P. carinii infection is delayed compared with wild-type controls. These CD40KO chimeric mice produced normal levels of P. carinii-specific IgM, but did not produce class-switched IgG or IgA. Similarly, clearance of P. carinii was delayed in mice deficient in Fc\u03b3RI and III (Fc\u03b3RKO), indicating that P. carinii-specific IgG partially mediates opsonization and clearance of P. carinii. Opsonization of organisms by complement did not compensate for the lack of specific IgG or Fc\u03b3R, since C3-deficient and C3-depleted Fc\u03b3RKO mice were still able to clear P. carinii. Finally, \u03bcMT and CD40KO chimeric mice had reduced numbers of activated CD4+ T cells in the lungs and lymph nodes compared with wild-type mice, suggesting that B cells are important for activation of T cells in response to P. carinii. Together these data indicate that P. carinii-specific IgG plays an important, but not critical, role in defense against P. carinii. Moreover, these data suggest that B cells also mediate host defense against P. carinii by facilitating CD4+ T cell activation or expansion.<\/jats:p>","DOI":"10.4049\/jimmunol.171.3.1423","type":"journal-article","created":{"date-parts":[[2014,4,20]],"date-time":"2014-04-20T21:29:45Z","timestamp":1398029385000},"page":"1423-1430","source":"Crossref","is-referenced-by-count":92,"title":["Clearance of\n                    <i>Pneumocystis carinii<\/i>\n                    in Mice Is Dependent on B Cells But Not on\n                    <i>P. carinii<\/i>\n                    -Specific Antibody"],"prefix":"10.1093","volume":"171","author":[{"given":"Frances E","family":"Lund","sequence":"first","affiliation":[{"name":"Trudeau Institute , Saranac Lake, NY 12983"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kevin","family":"Schuer","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Kentucky , Lexington, KY 40536"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melissa","family":"Hollifield","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Kentucky , Lexington, KY 40536"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Troy D","family":"Randall","sequence":"additional","affiliation":[{"name":"Trudeau Institute , Saranac Lake, NY 12983"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beth A","family":"Garvy","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Kentucky , Lexington, KY 40536"},{"name":"Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky , Lexington, KY 40536"},{"name":"Veterans Administration Medical Center , Lexington, KY 40536"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2003,8,1]]},"reference":[{"key":"2026020210193867600_R1","first-page":"640","volume-title":"Pharmacotherapy","year":"1993"},{"key":"2026020210193867600_R2","first-page":"543","volume-title":"Pediatrics","year":"1957"},{"key":"2026020210193867600_R3","first-page":"504","volume-title":"Am. 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