ELEVATED PLATELET-ASSOCIATED IGG IN THE THROMBOCYTOPENIA OF SEPTICEMIA

The mechanism of thrombocytopenia, a frequent complication of septicemia, is obscure, but indirect evidence suggests that the immune system may be involved. To investigate this possibility, we quantitated platelet-associated IgG on platelets obtained from 44 patients during 46 episodes of septicemia. Thrombocytopenia occurred in 21 of 46 episodes (46 per cent). Platelet-associated IgG was elevated in eight of 11 episodes of gram-negative septicemia and thrombocytopenia (47.3±11.7 fg of IgG per platelet [mean ± S.E.]) and in one of 20 patients with gram-negative septicemia and normal platelet counts (5.9±1.1) (P<0.001). Elevated levels occurred in eight of 10 patients with gram-positive septicemia and thrombocytopenia (55.3±14.7 fg of IgG per platelet) and in none of 11 patients with gram-positive septicemia and normal platelet counts (5.6±1.7) (P<0.001). Serial testing during the thrombocytopenia and recovery showed an inverse relation between the platelet count and platelet-associated IgG. Thrombocytopenia in some patients with septicemia may be related to the binding of IgG to platelets. (N Engl J Med 300:760–764, 1979) PATIENTS with septicemia often have hemostatic abnormalities that vary from a mild elevation in the serum concentration of fibrin degradation products to a rapidly fulminant state of disseminated intravascular coagulation.1,2 Thrombocytopenia is a common and prominent early finding in these cases.3 4 5 6 Although thrombocytopenia invariably accompanies disseminated intravascular coagulation, it is often observed in septicemic patients without evidence of that complication even when sensitive methods for detecting in vivo fibrin formation such as fibrinopeptide A assay or fibrinogen gel chromatography are used.7 The mechanism of thrombocytopenia in patients with septicemia who do not have evidence of disseminated intravascular coagulation is uncertain. © 1979, Massachusetts Medical Society. All rights reserved.