Moyron-Quiroz J E, Partida-Sánchez S, Donís-Hernández R, Sandoval-Montes C, Santos-Argumedo L
Department of Cellular Biology, Centro de Investigación y Estudios Avanzados del I.P.N., 07360 México D.F., México.
Scand J Immunol. 2002 Apr;55(4):343-51. doi: 10.1046/j.1365-3083.2002.01063.x.
In this work, we studied the expression and function of CD22 in murine B cells. CD22 has been previously characterized as an activation marker of mature B lymphocytes. However, we found that CD22 is expressed early during the ontogeny of B cells in the bone marrow and spleen, and was found on B cells isolated from all the different lymphoid compartments. We also found that B cells stimulated through the B-cell antigen receptor (BCR), CD38 and CD40, upregulated CD22 expression to maximal levels within 24 h after stimulation, but that the levels of CD22 declined at later times (48 and 72 h). CD22 is rapidly phosphorylated after BCR signal transduction, and is believed to downregulate B-cell activation. In this study, we did not detect CD22 phosphorylation in activated B cells after CD38 or CD40 cross-linking, even though CD22 was clearly phosphorylated in the BCR-stimulated B cells. Consistent with this, we found no evidence of physical association between CD38 or CD40 and CD22 in B cells. The lack of association or phosphorylation of CD22 induced by CD38 and CD40 cross-linking indicates that CD22 may not downregulate the activation induced by these two molecules.
在本研究中，我们研究了CD22在小鼠B细胞中的表达及功能。CD22先前已被表征为成熟B淋巴细胞的活化标志物。然而，我们发现CD22在骨髓和脾脏中B细胞的个体发育早期即有表达，并且在从所有不同淋巴区室分离出的B细胞上均能检测到。我们还发现，通过B细胞抗原受体（BCR）、CD38和CD40刺激的B细胞，在刺激后24小时内将CD22表达上调至最高水平，但CD22的水平在随后的时间（48和72小时）下降。BCR信号转导后CD22迅速磷酸化，并且被认为可下调B细胞活化。在本研究中，我们未检测到CD38或CD40交联后活化B细胞中的CD22磷酸化，尽管在BCR刺激的B细胞中CD22明显发生了磷酸化。与此一致，我们未发现B细胞中CD38或CD40与CD22之间存在物理关联的证据。CD38和CD40交联诱导的CD22缺乏关联或磷酸化表明，CD22可能不会下调由这两种分子诱导的活化。
