{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T10:27:00Z","timestamp":1760264820814},"reference-count":22,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2005,11,17]],"date-time":"2005-11-17T00:00:00Z","timestamp":1132185600000},"content-version":"vor","delay-in-days":5403,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Eur J Immunol"],"published-print":{"date-parts":[[1991,2]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The B subunit of cholera toxin (CT) but not the entire CT was found to induce the proliferation of resting human B lymphocytes. A significant mitogenic effect was observed for B subunit concentrations &gt; 1 \u03bcg\/ml and reached a maximum of stimulation at 10 \u03bcg\/ml. As already described for B lymphocytes preactivated with <jats:italic>Staphylococcus aureus<\/jats:italic> Cowan Strain I (SAC), B lymphocytes preactivated with the B subunit of CT, but not with the entire CT, were able to proliferate in response to exogenous interleukin 2 (IL 2) and to the low\u2010molecular weight B cell growth factor (BCGF).<\/jats:p><jats:p>To determine the transmembrane signaling system used by the B subunit of CT to mediate its biological effects, we compared the transmembrane signals used by the entire CT, its B subunit and SAC. In comparison to the entire CT, which directly activates adenylate cyclase and increases intracellular cAMP levels, neither the B subunit nor SAC modified the cAMP content. In contrast, although SAC induced inositol phosphate generation neither CT nor the separate subunits were able to induce such a production. Moreover, changes in the fluorescence of indo\u20101\u2010loaded B lymphocytes revealed that mitogenic doses of either the B subunit or SAC induced a rapid and sustained increase in cytoplasmic free Ca<jats:sup>2+<\/jats:sup> concentration ([Ca<jats:sup>2+<\/jats:sup>]i). The effect of the B subunit appeared to be largely dependent on the presence of extracellular Ca<jats:sup>2+<\/jats:sup>, because in Ca<jats:sup>2+<\/jats:sup>\u2010free medium no [Ca<jats:sup>2+<\/jats:sup>]i uptake was observed. In contrast, the SAC\u2010induced [Ca<jats:sup>2+<\/jats:sup>]i uptake is substantially, but not totally, inhibited in Ca<jats:sup>2+<\/jats:sup>\u2010free medium, suggesting that part of the rise in [Ca<jats:sup>2+<\/jats:sup>]i was due to the release from internal stores. Moreover, fluorimetric measurements on loaded cells with 2\u2032,7\u2032\u2010bis(carboxyethyl)\u20105(6\u2032)\u2010carboxyfluorescein revealed that SAC induced a rapid cytoplasmic alkalinization via activation of Na<jats:sup>+<\/jats:sup>\/H<jats:sup>+<\/jats:sup> exchange, whereas the entire CT and its B subunit had no effect on intracellular pH. Taken together, these data suggest that, in comparison to SAC, the mitogenic effect of the B subunit of CT was mediated through different intracellular biochemical pathways.<\/jats:p>","DOI":"10.1002\/eji.1830210236","type":"journal-article","created":{"date-parts":[[2007,3,1]],"date-time":"2007-03-01T12:40:45Z","timestamp":1172752845000},"page":"495-500","source":"Crossref","is-referenced-by-count":12,"title":["Effect of bacterial toxins on human B cell activation. II. Mitogenic activity of the B subunit of cholera toxin"],"prefix":"10.1002","volume":"21","author":[{"given":"Bernard","family":"Dugas","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nathalie","family":"Paul\u2010Eug\u00e8ne","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elisabeth","family":"G\u00e9not","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jean Michel","family":"Mencia\u2010Huerta","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pierre","family":"Braquet","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jean Pierre","family":"Kolb","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2005,11,17]]},"reference":[{"key":"e_1_2_1_2_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.bi.54.070185.000445"},{"key":"e_1_2_1_3_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.bi.56.070187.003151"},{"key":"e_1_2_1_4_2","first-page":"556","volume":"109","author":"Ribiero\u2010Neto F. 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