MONOCLONAL ANTI-IGM REGULATION OF HUMAN B CELL FUNCTION

拟议的研究将探讨配体相互作用的性质 具有B淋巴细胞刺激所需的膜IgM。 这将 通过使用一组抗人IgM单克隆抗体 抗体（MoAb），其在亲和力和/或表位特异性方面不同。 使用这些定义的抗Ig配体，解释了不同的免疫球蛋白， 过去已经观察到的抗Ig配体的调节作用 将被寻求。 这些研究可以阐明决定 是否有自体抗Ig恒定区抗体（类风湿性 因子）可以调节它们所结合的B细胞的功能。 比较不同鼠抗人IgM单克隆抗体的抗人IgM能力 a）诱导静息B细胞增殖，B）影响增殖 和用其它促分裂剂刺激的B细胞的分化，和c） 刺激细胞S期之前的B细胞的早期变化 周期 一旦刺激性和非刺激性（可能是抑制性） 已经鉴定出MoAb，解释了MoAb的功能差异。 将寻找这些配体。 这将涉及比较刺激和 非刺激性MoAb及其F（ab '）2片段，用于a）亲和力和 与IgM结合的化学计量和B）表位特异性。 表位 将通过竞争性抑制研究单克隆抗体的特异性 通过研究和分析每种单克隆抗体的化学结合能力， 修饰的IgM、IgM片段和合成的肽， 通过亲水性和构象分析预测， 构成人IgM分子上的免疫原性表位。 此外，膜分子交联的性质， 将研究刺激B细胞增殖所必需的量。 这将 涉及比较二价抗IgM单抗与 由一个针对IgM的F（ab ′）臂和一个针对IgM的F（ab ′）臂组成的杂交抗体， 针对人主要组织相容性（MHC）抗原的F（ab '）臂。

The proposed study will investigate the nature of the ligand interaction with membrane IgM which is needed for B lymphocyte stimulation. This will be accomplished through the use of a panel of anti-human IgM monoclonal antibodies (MoAbs) which differ in affinity and/or epitope specificity. Using these defined anti-Ig ligands, an explanation for the diverse regulatory effects of anti-Ig ligands which have been observed in the past will be sought. These studies may elucidate the factors that determine whether or not autologous anti-Ig constant region antibodies (rheumatoid factors) can regulate the function of B cells to which they bind. The different mouse anti-human IgM MoAbs will be compared in their ability to a) induce resting B cells to proliferate, b) affect the proliferation and differentiation of B cells stimulated with other mitogens, and c) stimulate early changes in B cells which precede the S phase of the cell cycle. Once sets of stimulatory and non-stimulatory (perhaps inhibitory) MoAbs have been identified, explanations for the functional differences in these ligands will be sought. This will involve comparing stimulatory and non-stimulatory MoAbs and their F(ab')2 fragments for a) affinity and stoichiometry of binding to IgM and b) epitope specificity. The epitope specificity of the MoAbs will be investigated by competitive inhibition studies and by analysis of the ability of each MoAb to bind to chemically modified IgM, IgM fragments, and synthesized peptides which have been predicted by hydrophilicity and conformational analysis as likely to constitute immunogenic epitopes on the human IgM molecule. In addition, the nature of membrane molecule crosslinkage which is necessary to stimulate B cell proliferation will be studied. This will involve comparing the mitogenic capacity of a divalent anti-IgM MoAb to a hybrid antibody which consists of one F(ab') arm directed to IgM and one F(ab') arm directed to a human major histocompatibility (MHC) antigen.