An object of the present invention is to provide a novel drug for preventing, suppressing the progress of symptoms, suppressing the recurrence or treating for autoimmune diseases.As a result of intensive investigations, the inventors of the present invention focused on PD-1 / CD3 bispecific antibodies as substances capable of solving such problems, and have confirmed that they can be a formulation to reduce the occurrence of side effects called infusion reaction or cytokine release syndrome. In addition, it has been confirmed that the bispecific antibody has a feature that permits interaction with PD-1 and its ligand PD-L1, and has been found that such characteristics contribute to the enhancement or continuation of action.本發明的課題係提供一種新穎的藥劑，該藥劑係用以預防、抑制症狀進展、抑制復發或治療自體免疫疾病。本發明的發明者等進行深入研究的結果，著眼於PD-1/CD3雙特異性抗體作為能夠解決該等問題的物質，並且確認此等可作為減輕被稱為輸注反應或細胞介素釋出症候群之副作用的製劑。再者，已確認該雙特異性抗體具有容許PD-1與屬於其配位體之PD-L1相互作用的特徵，並且發現如此之特徵有助於增強或持續地作用。
