Rh factor is
High-Yield Explanation
A i.e. IgM antibody - Rheumatoid (Rh) factor in rheumatoid ahritis is an autoantibody of IgM class directed against Fc fragment of IgGQ. - Antibodies (immunoglobins) are glycoproteins. And Rh factors is an autoantibody of any immunoglobin class directed against Fc fragment of IgG immunoglobin (Davidson).