Brutkiewicz R R, O'Donnell C L, Maciaszek J W, Welsh R M, Vargas-Cortes M
Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.
Eur J Immunol. 1993 Oct;23(10):2427-33. doi: 10.1002/eji.1830231008.
We have previously described a monoclonal antibody (mAb), CZ-1, which reacts with an epitope expressed on most peripheral basophils, natural killer cells, B cells, and CD8+ T cells, but not with most thymocytes or peripheral CD4+ T cells. Here we show that mAb CZ-1 defines a sialic acid-dependent epitope associated with a subpopulation of CD45 molecules. This conclusion is based on the ability to block binding of mAb CZ-1 by sialic acid, neuramin-lactose, neuraminidase, and mAb to CD45RB, and by expression of the epitope on transfected psi 2 cells expressing exon B of CD45. The results suggest that the CZ-1 epitope is a post-translational modification expressed on a subpopulation of the CD45 molecules also expressing the B exon. Expression of the CZ-1 epitope was required for freshly isolated lymphocytes to respond to interleukin-2 (IL-2). Depletion of CZ-1+ cells by C' or by cell sorting of thymocytes or splenocytes eliminated the IL-2 responsive cells. The subpopulations of thymocytes and CD4+ splenocytes responding to IL-2 were exclusively within the small CZ-1+ subpopulation. mAb CZ-1 was also used to subdivide CD45+ and CD45RB+ splenocytes into IL-2-responsive and -nonresponsive subpopulations. The CZ-1 epitope was also expressed on virtually all lymphokine-activated killer cell precursors. These data, thus, indicate that cells responsive to IL-2 express this sialated modification of CD45.
我们之前描述过一种单克隆抗体（mAb），即CZ-1，它能与大多数外周嗜碱性粒细胞、自然杀伤细胞、B细胞和CD8⁺T细胞上表达的一个表位发生反应，但不与大多数胸腺细胞或外周CD4⁺T细胞发生反应。在此我们表明，mAb CZ-1界定了一个与CD45分子亚群相关的唾液酸依赖性表位。这一结论基于唾液酸、神经氨酸乳糖、神经氨酸酶和抗CD45RB单克隆抗体阻断mAb CZ-1结合的能力，以及该表位在表达CD45外显子B的转染psi 2细胞上的表达情况。结果表明，CZ-1表位是一种在也表达B外显子的CD45分子亚群上表达的翻译后修饰。新鲜分离的淋巴细胞对白细胞介素-2（IL-2）作出反应需要CZ-1表位的表达。通过补体（C'）或对胸腺细胞或脾细胞进行细胞分选去除CZ-1⁺细胞，消除了IL-2反应性细胞。对IL-2作出反应的胸腺细胞和CD4⁺脾细胞亚群仅存在于小的CZ-1⁺亚群内。mAb CZ-1还被用于将CD45⁺和CD45RB⁺脾细胞细分为对IL-2有反应和无反应的亚群。CZ-1表位实际上也在所有淋巴因子激活的杀伤细胞前体上表达。因此，这些数据表明，对IL-2有反应的细胞表达这种CD45的唾液酸化修饰。
