<unk>  <unk>  is the autoantibody that was first found in<unk>  arthritis. It is defined as an antibody against the Fc portion of IgG and different<unk> s can recognize different parts of the IgG-Fc.<unk>  and IgG join to form immune complexes that contribute to the disease process.<unk>  can also be a cryoglobulin (antibody that precipitates on cooling of a blood sample); it can be either type 2 (monoclonal IgM to polyclonal IgG) or type 3 (polyclonal IgM to polyclonal IgG) cryoglobulin. Although predominantly encountered as IgM,<unk>  can be of any isotype of immunoglobulins, i.e. IgA, IgG, IgM, IgE, IgD.
Rheumatoid factor
C-ANCA
Antisperm antibodies
Anti–citrullinated protein antibody
Anti-neutrophil cytoplasmic antibody
Microantibody
Anti-nuclear antibody
ANA-12