It is also called type IV hypersensitivity or delayed hypersensitivity. This immune reaction differs from the other three types of allergic reactions in that it is not caused by antibodies, but by lymphocytes. It is a specific reaction between lymphocytes and tissue antigens or small molecules which, when fixed to the cell membrane, can function as an antigen, leading to tissue damage. Classic examples are the positive tuberculin reaction, contact dermatitis (e.g. caused by nickel or chrome) and rejection of transplanted tissues.