Platelet-associated complement C3 in immune thrombocytopenic purpura
TJ Myers, BK Kim, M Steiner and MG Baldini
Platelet-associated C3 (PA-C3) was measured with a quantitative
immunofluorescence assay. With this assay, PA-C3 levels were determined for
78 normal volunteers, 30 patients with immune thrombocytopenic purpura
(ITP), and 20 patients with nonimmune thrombocytopenias.
Platelet-associated IgG (PA-IgG) levels were also measured with our
standard quantitative immunofluorescence assay. All patients with nonimmune
thrombocytopenias and ITP in remission had normal PA-C3 levels. Twenty-four
patients with active ITP were classified into 3 groups: 9 (38%) with
increased PA-IgG and normal PA-C3 levels, 10 (42%) with elevated PA-C3 and
PA-IgG levels, and 5 (20%) with increased PA-C3 values only. A direct
correlation was found between PA-C3 and PA-IgG levels. PA-IgG levels were
higher in the group of patients with elevated PA-C3 levels than in those
with normal values. Platelet survival studied showed reduced survival times
of 1.5--2.5 days for the 5 patients with elevated PA-C3 levels only.
Elevated PA-C3 levels returned to normal in 7 ITP patients whose platelet
counts increased in response to corticosteroid therapy or to splenectomy.
Therefore, PA-C3 and PA-IgG assays can be used to identify patients with
ITP, to follow their response to therapy, and to classify them into
immunologic subgroups similar to red cell classification by Coombs' testing
in immune hemolytic anemia.
Volume 59,
Issue 5,
pp. 1023-1028,
05/01/1982
Copyright © 1982 by The American Society of Hematology
