Hadley A G, Zupanska B, Kumpel B M, Leader K A
International Blood Group Reference Laboratory, Bristol, U.K.
Immunology. 1992 Jul;76(3):446-51.
Subsets of human lymphocytes were isolated from peripheral blood using magnetic beads coated with anti-CD4, -CD8, -CD19 or -CD56 antibodies to yield T4, T8, B and natural killer (NK) cell suspensions with greater than 95% purity. The functional activity of Fc gamma receptor II (Fc gamma RII) and Fc gamma receptor III (Fc gamma RIII) on these subsets was assessed by measuring rosette formation with red cells sensitized with known levels of either rabbit IgG or human (monoclonal or polyclonal) IgG1 anti-D, IgG3 anti-D or IgG3 anti-c (E-IgG). Lysis of red cells by K cells (mediated by Fc gamma RIII) in antibody-dependent cell-mediated cytotoxicity (ADCC) assays was promoted by polyclonal and some monoclonal antibodies. Using these 'ADCC+' antibodies, minimum red cell sensitization levels required to promote rosette formation with NK cells were 2000 IgG1 or IgG3 molecules/red cell compared to 15,000 IgG1 or 4000 IgG3 molecules/red cell with 'ADCC-' monoclonal antibodies. The greater efficiency of ADCC+ antibodies is consistent with their previously reported ability to bind Fc gamma RIII via CH2 and CH3 domains whereas ADCC- antibodies bind only via CH3 domains. B cells formed rosettes only at high levels of sensitization: approximately 60,000 IgG1 or 20,000 IgG3 anti-D molecules/cell. These data reflect the low affinity of Fc gamma RII for monomeric human IgG. Although over 90% of NK cells bound anti-CD16, and 70% formed rosettes with red cells sensitized with rabbit IgG (30,000 molecules/cell), only 25% of NK cells formed rosettes with E-IgG3 at 100,000 IgG molecules/cell. Approximately 35% of B cells, 10% of T8 cells but no T4 cells formed rosettes with E-IgG (100,000 IgG3 molecules/cell). With T8, B and NK cells, IgG3 anti-D promoted greater rosette formation than IgG1 anti-D at comparable levels of sensitization. Presumably the longer hinge region of IgG3 enabled it to bridge the gap between negatively charged lymphocytes and red cells more efficiently than IgG1.
使用包被有抗CD4、抗CD8、抗CD19或抗CD56抗体的磁珠从外周血中分离人淋巴细胞亚群，以获得纯度大于95%的T4、T8、B和自然杀伤（NK）细胞悬液。通过测量与用已知水平的兔IgG或人（单克隆或多克隆）IgG1抗-D、IgG3抗-D或IgG3抗-c（E-IgG）致敏的红细胞形成的玫瑰花结，评估这些亚群上Fcγ受体II（FcγRII）和Fcγ受体III（FcγRIII）的功能活性。在抗体依赖性细胞介导的细胞毒性（ADCC）试验中，多克隆抗体和一些单克隆抗体促进了K细胞（由FcγRIII介导）对红细胞的裂解。使用这些“ADCC+”抗体，促进NK细胞形成玫瑰花结所需的最低红细胞致敏水平为2000个IgG1或IgG3分子/红细胞，而使用“ADCC-”单克隆抗体时为15000个IgG1或4000个IgG3分子/红细胞。ADCC+抗体更高的效率与其先前报道的通过CH2和CH3结构域结合FcγRIII的能力一致，而ADCC-抗体仅通过CH3结构域结合。B细胞仅在高致敏水平下形成玫瑰花结：约60000个IgG1或20000个IgG3抗-D分子/细胞。这些数据反映了FcγRII对单体人IgG的低亲和力。尽管超过90%的NK细胞结合抗CD16，且70%的NK细胞与用兔IgG（30000个分子/细胞）致敏的红细胞形成玫瑰花结，但在100000个IgG分子/细胞时，只有25%的NK细胞与E-IgG3形成玫瑰花结。约35%的B细胞、10%的T8细胞但没有T4细胞与E-IgG（100000个IgG3分子/细胞）形成玫瑰花结。对于T8细胞、B细胞和NK细胞，在相当的致敏水平下，IgG3抗-D比IgG1抗-D促进更多的玫瑰花结形成。据推测，IgG3较长的铰链区使其能够比IgG1更有效地弥合带负电荷的淋巴细胞和红细胞之间的间隙。
