A method of detecting cell membrane expression of an MHC molecule in a subject, a method of treating cancer in a subject with an immunotherapeutic agent, and an MHC complex are provided. The method of detecting cell membrane expression of an MHC molecule includes obtaining a tumor cell sample from a subject, and detecting cell membrane expression of the MHC molecule by contacting the tumor cell sample with an antibody targeting the MHC molecule and detecting binding between the MHC molecule and the antibody. The method of treating cancer in a subject with an immunotherapeutic agent includes detecting cell membrane expression of an MHC molecule in the subject and administering a therapeutically effective amount of the immunotherapeutic agent if the level of cell membrane expression of the MHC molecule exceeds a predetermined standard. The complex includes a tumor cell in complex with an antibody or an antigen-binding portion thereof.