Functional role of CD43 in immune system

CD43是一种主要的造血细胞表面唾液酸蛋白，其胞外结构域具有高度的O-糖基硅酸化，其在造血系统中的功能作用尚不完全清楚；为了分析CD43在B细胞中的生物学效应，我们将小鼠CD43基因转入B细胞淋巴瘤细胞株WEHI 231中，并与亲本细胞系、人CD8转染体和由CD43~+克隆建立的CD43~-反转体的生长和存活进行了比较。结果支持CD43可能在B细胞系细胞存活中起一定作用的观点。结果也支持CD43与其配体之间的相互作用对CD43的生物学效应有影响。为了研究CD43在B细胞存活和激活中的作用，我们建立了两个CD43转基因小鼠，并使用了一个拷贝数高于另一个的品系。在体外，CD43转基因小鼠脾细胞中CD43的表达水平比非转基因小鼠高约10倍。其中CD43转基因小鼠的脾细胞产生的LGM抗体水平约为非转基因小鼠的3倍。在DNP-KLH的初次免疫中，转基因小鼠产生的LGM抗体是非转基因小鼠的2-3倍。体外和体内的结果与CD43的表达可能在分化为LGM抗体形成细胞和其存活过程中起到一定的作用这一观点是一致的。

CD43 is a major surface sialoprotein on hemopoietic cells, whose extracellular domain is heavily O-glycosilated.The functional role of CD43 in the hemopoietic system is not fully understood ; however, it has been suggested that CD43 may have a role in cell-cell repulsion and in modifying T-cell proliferation and activation.In order to analyze the biological effect of CD43 in B-lineage cells, we transfected murine CD43 cDNA into a CD43^- B-cell lymphoma, WEHI 231, and the growth and survival in culture were compared to those of a parental cell line, human CD8 transfectants, and CD43^- revertants established from CD43^+ clones.The results support the notion that CD43 may have some role in cell survival of B-lineage cells, probably reflected by the resistance to apoptosis and progression of the cell cycle.The results also support the notion that interaction between CD43 and its ligand, either expressed on the surface of or secreted from WEHI 231 has a role for the biological effect of CD43.In order to characterize the role of CD43 in B cell survival and activation, we established two CD43 transgenic mice and used one of the line who carries copy numbers higher than another.Expression of CD43 was up-regulated in splenocytes of CD43 transgenic mice at the level approximately 10 times higher than that of non-transgenic mice upon stimulation with LPS in vitro, in which splenocytes of CD43 transgenic mouse produced lgM antibodies approximately 3 times above the level of non-transgenic mose.In primary immunization with DNP-KLH,the transgenic mice produced lgM antibodies 2-3 times above the level of non-transgenic mice.The results in vitro and in vivo are compatible with the idea that the expression of CD43 may play some role in differentiation into lgM antibody-forming cells and their survival.Furthe analysis of cell dynamics in immunized mice is now inder investigation.