Winkler T H, Rolink A, Melchers F, Karasuyama H
Basel Institute for Immunology, Switzerland.
Eur J Immunol. 1995 Feb;25(2):446-50. doi: 10.1002/eji.1830250221.
Two monoclonal antibodies raised against the complex of mu heavy (H) chain and Vpre-B/lambda 5 surrogate light (L) chains recognize surrogate L chain in different conformations on normal pre-B cells. One, LM34 recognizes free lambda 5 protein and free lambda 5/Vpre-B surrogate L chains and binds to surrogate L chains on the surface of early, pro-B and pre-B-I cells where the surrogate L chain is associated with a gp130/gp35-65 complex of proteins. It also recognizes the surrogate L chain associated with the mu H chain on pre-B-II cells. The other monoclonal antibody, SL156, does not recognize free surrogate L chain or its components, nor its complex with gp130/gp35-65 on pro-B and pre-B-I cells. However, it does bind to a conformational epitope on the surrogate light chain/mu H chain complex on a subpopulation of pre-B-II cells and on mu H chain-positive pre-B cell lines. On mouse precursor B cells prepared ex vivo on ice, expression of the surrogate L chain is very low and almost undetectable. Incubation of the precursor cells for 1 h at 37 degrees C up-regulates the surface expression of surrogate L chain associated with gp130/gp35-65 (early complex) as well as the mu H chain/surrogate L chain complex. These results reconcile some of the apparently discrepant results on surface expression of the surrogate L chain obtained with human and mouse bone marrow pre-B cells, and show that a surrogate L chain/mu H chain-containing pre-B cell receptor can be expressed also on the surface of mouse pre-B-II cells.
两种针对μ重链（H）与Vpre-B/λ5替代轻链（L）复合物产生的单克隆抗体，可识别正常前B细胞上不同构象的替代轻链。一种是LM34，可识别游离的λ5蛋白和游离的λ5/Vpre-B替代轻链，并与早期前B细胞、原B细胞和前B-Ⅰ细胞表面的替代轻链结合，此时替代轻链与gp130/gp35-65蛋白复合物相关联。它还能识别前B-Ⅱ细胞上与μ重链相关的替代轻链。另一种单克隆抗体SL156，不识别游离的替代轻链或其组分，也不识别其与原B细胞和前B-Ⅰ细胞上gp130/gp35-65的复合物。然而，它确实能与前B-Ⅱ细胞亚群以及μ重链阳性前B细胞系上替代轻链/μ重链复合物上的一个构象表位结合。在冰上离体制备的小鼠前体B细胞上，替代轻链的表达非常低，几乎检测不到。将前体细胞在37℃孵育1小时，可上调与gp130/gp35-65相关的替代轻链（早期复合物）以及μ重链/替代轻链复合物的表面表达。这些结果调和了用人和小鼠骨髓前B细胞获得的关于替代轻链表面表达的一些明显矛盾的结果，并表明含替代轻链/μ重链的前B细胞受体也可在小鼠前B-Ⅱ细胞表面表达。
