HETEROGENEITY OF HUMAN CIRCULATING ANTICOAGULANTS AGAINST ANTIHEMOPHILIC-FACTOR (FACTOR 8)

Abstract

The heterogeneity of human circulating anticoagulants against antihemophilic factor (AHF, factor VIII) observed in 7 patients, with and without classic hemophilia, was investigated by neutralization of their activity with antiserums directed to whole IgG [immunoglobulin G] and to .lambda. and .kappa. L chains. All 7 anticoagulants were Ig. Six appeared to contain both kinds of L chains, although the dual L chain composition of 2 of these could be demonstrated only at high concentration of antiserum. In 1 circulating anticoagulant, L chain specificity could not be demonstrated with small amounts of antiserum, and with larger amounts, only .lambda. L chain specificity was revealed. Whether or not this circulating anticoagulant really contained a single L chain type could not be ascertained with this technique. Circulating anticoagulant antibodies against AHF are probably polyclonal in nature.