Molecular design of polymer with lymphocyte-activating ability

我们发现含有苯硼酸片段的水溶性聚合物具有诱导小鼠淋巴细胞增殖的能力。这可能是由于聚合物中的苯硼酸残基与淋巴细胞质膜表面存在的糖残基结合所致。在这种情况下，苯硼酸盐聚合物作为淋巴细胞的人工丝裂原。苯硼酸在水环境中具有三角形硼酸盐和四面体硼酸盐之间的平衡。只有四面体硼酸盐与糖形成稳定的配合物。但由于苯硼酸的pKa较高，生理状态下只有少量四面体硼酸盐存在（pH7.4）。为了提高生理条件下的有丝分裂活性，本研究在含硼酸盐聚合物中引入氨基，促进硼酸盐与质膜上的糖残基形成复合物，从而提高淋巴细胞的增殖能力。由此合成了N，N-二甲基丙烯酰胺、3-丙烯酰胺苯硼酸和N，N-二甲氨基丙烯酰胺（DMAPAA）三元共聚物。通过加入^ 3h -胸腺嘧啶来评价小鼠淋巴细胞的增殖反应。与不含氨基的DB相比，DBA培养的淋巴细胞对^ 3h -胸苷的摄取显著增加。这种有丝分裂能力的增加似乎是由于在DBA中，氨基与苯硼酸部分协调，从而有效地形成了细胞膜上硼酸盐和糖残基之间的复合物。在淋巴细胞增殖方面，DBA共聚物的氨基含量达到最佳，表明DBA的氨基含量在淋巴细胞增殖中起关键作用。

We have found that water soluble polymer having phenylboronic acid moiety has ability to induce mouse lymphocytes proliferation. This might be due to the binding of phenylboronic acid residues in the polymer to sugar residues existing on the plasma membrane surface of lymphocytes. In this context, phenylboronate polymer serves as artificial mitogen of lymphocytes. phenylboronic acid is known to have an equilibrium between trigonal form and tetrahedral borate form in aqueous milieu. Only tetrahedral borate forms a stable complex with sugar. However, due to the relatively high pKa of phenylboronic acid, there exists only a small amount of tetrahedral boronate at physiological condition (pH7.4). To increase mitogenic activity under physiological condition, amino groups were introduced into the borate-containing polymer in this study to facilitate complex formation of boronate with sugar residues on the plasma membrane, allowing to achieve an increased ability to proliferate lymphocytes. Thus, ternary copolymer (DBA) of N,N-dimethylacrylamide, 3-acrylamidophenylboronic acid and N,N-dimethylaminopropylacrylamide (DMAPAA) was synthesized. Proliferative response of mouse lymphocytes was evaluated from incorporation of ^3H-thymidine. Remarkable increase in ^3H-thymidine uptake to lymphocytes was observed for lymphocytes cultured with DBA compared to that with DB which has no amino groups. This increase in mitogenic ability seems to be due to the effective formation of the complex between boronate and sugar residues on the cell membrane because of the coordination of amino groups to phenylboronic acid moieties in DBA.There was observed an optimum amino group content in the DBA copolymer in terms of lymphocyte proliferation, indicating a crucial role of amino group content of DBA in lymphocyte proliferation.