Antibodies to actin in autoimmune haemolytic anaemia.
BACKGROUND
In autoimmune haemolytic anaemia (AIHA), autoreactive antibodies directed against red blood cells are up-regulated, leading to erythrocyte death. Mycoplasma suis infections in pigs induce AIHA of both the warm and cold types. The aim of this study was to identify the target autoantigens of warm autoreactive IgG antibodies. Sera from experimentally M. suis-infected pigs were screened for autoreactivity.


RESULTS
Actin-reactive antibodies were found in the sera of 95% of all animals tested. The reactivity was species-specific, i.e. reactivity with porcine actin was significantly higher than with rabbit actin. Sera of animals previously immunised with the M. suis adhesion protein MSG1 showed reactivity with actin prior to infection with M. suis indicating that molecular mimicry is involved in the specific autoreactive mechanism. A potentially cross-reactive epitope was detected.


CONCLUSIONS
This is the first report of autoreactive anti-actin antibodies involved in the pathogenesis of autoimmune haemolytic anaemia.
Felder
Kathrin M
KM
Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Zurich, Switzerland.
Hoelzle
Katharina
K
Heinritzi
Karl
K
Ritzmann
Mathias
M
Hoelzle
Ludwig E
LE
D000199:Actins / Q000276:immunology*; D000744:Anemia, Hemolytic, Autoimmune / Q000209:etiology / Q000276:immunology / Q000662:veterinary*; D000818:Animals; D003001:Cloning, Molecular; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D009175:Mycoplasma Infections / Q000150:complications / Q000662:veterinary; D011817:Rabbits; D013156:Splenectomy; D013552:Swine; D013553:Swine Diseases / Q000276:immunology*
D000199:Actins; D007074:Immunoglobulin G