Therefore, in this study, a single-domain antibody against CD20, a protein on the surface of human B-cell lymphoma, and a single-domain antibody against CD3, a molecule on the surface of T cells, were fused to construct a novel bispecific single-domain antibody, which confers the advantages of small molecular weight, easy production, and high stability and affinity and can be administered by multiple routes [32]. Here, MS4A1 is linked to B-cell non-Hodgkin lymphoma.