Antiplatelet antibodies in WASP(-) mice correlate with evidence of increased in vivo platelet consumption.
OBJECTIVE
To study the role of antiplatelet antibodies in the thrombocytopenia of murine Wiskott-Aldrich syndrome (WAS).


METHODS
A flow cytometric method was developed for detection of serum antiplatelet antibodies via their binding to intact target platelets lacking surface antibodies. Platelets were labeled with 5-chloromethylfluorescein diacetate (CMFDA) in order to track their clearance from the circulation. WASP(-)muMT(-/-) mice were generated by standard breeding methods.


RESULTS
Serum antiplatelet antibodies were detected in approximately 40% of WASP(-) males. The mean level of reticulated platelets is significantly increased in these antibody(+) males. While WASP(-) males show an approximately 50% reduction in platelet counts, 5% to 10% show a more severe thrombocytopenia associated with increased reticulated platelets, suggesting the presence of clearance-inducing antiplatelet antibodies. In support of that inference, 90% of the latter mice show detectable serum antiplatelet antibodies. The antibodies are primarily immunoglobulin G, and are also detected in >30% of CD47(-/-) males. WASP(-)muMT(-/-) males, which demonstrate no serum- or platelet-associated antibodies, show a degree of thrombocytopenia similar to that of WASP(-) males. Their platelet clearance rates remain accelerated--more so in WASP(-)muMT(-/-) than WASP(+)muMT(-/-) recipients.


CONCLUSIONS
These findings suggest that platelet WASP deficiency results in an increase in platelet clearance rates by two mechanisms: an antibody-independent mechanism that largely requires WASP deficiency in trans, and an antibody-dependent mechanism that does not. Both an increased incidence of antiplatelet antibodies and an increased susceptibility to their effects contribute to antibody-dependent clearance of WASP(-) platelets.
Marathe
Bindumadhav M
BM
Department of Pathology and Laboratory Medicine, University of Tennessee Health Sciences Center, Memphis, Tenn., USA.
Prislovsky
Amanda
A
Astrakhan
Alexander
A
Rawlings
David J
DJ
Wan
Jim Y
JY
Strom
Ted S
TS
D000818:Animals; D001323:Autoantibodies / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000473:pathology; D001792:Blood Platelets / Q000276:immunology*; D001853:Bone Marrow / Q000473:pathology; D051928:CD47 Antigen / Q000235:genetics / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D009895:Opsonin Proteins / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology / Q000502:physiology; D010976:Platelet Count; D013154:Spleen / Q000473:pathology; D013163:Splenomegaly / Q000209:etiology / Q000473:pathology; D014923:Wiskott-Aldrich Syndrome / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000473:pathology; D051316:Wiskott-Aldrich Syndrome Protein / Q000172:deficiency*
D001323:Autoantibodies; D051928:CD47 Antigen; C497895:Cd47 protein, mouse; D009895:Opsonin Proteins; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein