Rh factor is a:
A Rheumatoid factor is an antibody (auto-antibody) of any immunoglobulin class directed against a specific region of the Fc fragment of human IgG. Ref: Harrison's Principles of Internal Medicine, 17th Edition, Page 2155; Davidson's Principles and Practice of Medicine, 20th Edition, Page 1074
Antibody
Mucopolysaccharide
Lipoprotein
Glycoprotein