Poppema S, Lai R, Visser L
Department of Laboratory Medicine, Cross Cancer Institute, Edmonton, Alberta, Canada.
J Immunol. 1991 Jul 1;147(1):218-23.
MT3 is a new antibody reactive with a restricted isoform of the leukocyte common Ag (CD45) family. The Ag is mainly expressed on T lymphocytes and thymocytes. It is differentially expressed on B cell subpopulations, with no staining of the majority of small follicular mantle zone B cells but positive staining of the majority of marginal zone B cells of spleen. Like most CD45 antibodies, reactivity can be demonstrated in fresh frozen as well as in formalin-fixed, paraffin-embedded tissues. This reactivity clearly differs from all other published anti-CD45 antibodies. In immunoprecipitation and Western blot procedures, the antibody reacts with a major band with a molecular mass of 190 kDa and weak bands with molecular masses of 205 and 220 kDa. Compared to antibody PD7 that reacts with exon B-encoded sequences, the reactivity with the 205 and 220 bands is much weaker. This is reflected in MT3 reactivity with leukocyte common Ag transfectants that include exon B-encoded sequences, such as AB and B, but not with those that also include C-encoded sequences, such as ABC or BC. It can be concluded that MT3 recognizes additional heterogeneity in the leukocyte common Ag complex, that is based on the differential expression of sialic acid-dependent determinants associated with exon B-encoded sequences.
MT3是一种新型抗体，可与白细胞共同抗原（CD45）家族的一种限制性异构体发生反应。该抗原主要表达于T淋巴细胞和胸腺细胞上。它在B细胞亚群中呈差异表达，大多数小滤泡套区B细胞无染色，但脾脏的大多数边缘区B细胞呈阳性染色。与大多数CD45抗体一样，在新鲜冷冻组织以及福尔马林固定、石蜡包埋组织中均可显示其反应性。这种反应性明显不同于所有其他已发表的抗CD45抗体。在免疫沉淀和蛋白质印迹实验中，该抗体与一条分子量为190 kDa的主要条带以及分子量为205和220 kDa的弱条带发生反应。与与外显子B编码序列发生反应的抗体PD7相比，其与205和220条带的反应性要弱得多。这在MT3与包含外显子B编码序列（如AB和B）的白细胞共同抗原转染子的反应性中得到体现，但与那些还包含C编码序列（如ABC或BC）的转染子无反应。可以得出结论，MT3识别白细胞共同抗原复合物中的额外异质性，这是基于与外显子B编码序列相关的唾液酸依赖性决定簇的差异表达。
