Interleukin 10

Interleukin 10 is a inhibitory cytokine which is secreted primarily by activated B-cells and T-cells; which include T-helper cells and T-reg cells. 

IL-10 turns off the immune responses and it does this by inhibiting other cells, which stops them from presenting the antigen, therefore the antibodies have nothing to bind to, so it will not illicit an immune response.