Measurement of factor VIII CAg by immunoradiometric assay in human tissue extracts

Samples of normal tissues taken from three patients within 24 hours of death were physically disrupted, washed and extracted. Centrifuged supernatants were tested for factor VIII coagulant antigen (VIII CAg) and factor VIII related antigen (VIII RAg) by radioimmunoassays using homologous and heterologous antisera respectively. VIII RAg was readily washed out by isotonic saline whereas VIII CAg required 1.5 M sodium chloride for optimal extraction from tissue homogenates. Highest levels of VIII CAg were detected in some lymph nodes followed by lung, liver and spleen. There was rapid loss of VIII CAg from most tissues in the absence of proteolytic inhibitors.