Investigations were undertaken of the chemical nature and kinetics of interaction of three acquired inhibitors of Factor VIII. The inhibition was stoichiometric, one molecule of inhibitor (or one site on a molecule) being required to inactivate one molecule of Factor VIII. All three inhibitors were found to be monotypic antibodies of class IgG, Type K (γ2 κ2). This appears to be the second syndrome due to the production of monotypic antibody, and the first instance involving IgG immunoglobulins.
Sandor S. Shapiro