Fc–Fc interactions and immune inhibitory effects of IgG4: implications for anti-PD-1 immunotherapies ====================================================================================================== * Weifeng Zhang * Xueling Chen * Xingxing Chen * Jirui Li * Hui Wang * Xiaomiao Yan * Han Zha * Xiaonan Ma * Chanyuan Zhao * Meng Su * Liangli Hong * Penghao Li * Yanyu Ling * Wenhui Zhao * Yu Xia * Baiyong Li * Tianjing Zheng * Jiang Gu