The Activation of Factor X by Extracts of Rabbit Brain

Thromboplastic preparations were obtained from rabbit brain. The dataindicate that standard acetone-dried reagent functions by activating factorX, with factor VII as an accelerator. When crude tissue reagent was fractionated by butanol treatment and saline extraction, a water-soluble materialwas obtained which similarly activated factor X. In each case, a source ofphosphatide was necessary for activated factor X to yield full clotting activity;this phosphatide was provided in the crude tissue reagent but it was lacking in the water-soluble extract.

The extract was further purified and characterized. It appears to be aprotein and it evidently activates factor X enzymatically. The data thusindicate that brain thrombloplastin contains two separable clotting activities:one of these activates factor X, the other supplies phosphatide.

Submitted on July 21, 1963 Accepted on November 16, 1963     

Studies on the genetics of leukocyte antigens

A panel of sera with leukoagglutinin activity was obtained from patientswho had received multiple blood transfusions. Leukocytes of identical twinspresented identical reaction patterns when tested against these sera, althoughno two unrelated subjects had identical leukocytes. None of the sera hadidentical reaction patterns with a panel of leukocytes from different subjects.Family studies failed to identify specific leukocyte antigens. It is concludedthat there is a multiplicity of leukocyte antigens and that these are notrelated to erythrocyte antigens. The data suggest that febrile transfusionreactions in patients with leukoagglutinins may be avoided by use of bloodswith compatible leukocytes.

Submitted on August 21, 1958 Accepted on November 30, 1958     

Neonatal Neutropenia Due to Maternal Isoimmunization

A family is reported with multiple cases of neonatal neutropenia. The firstchild died of severe infection, the second was asymptomatic, the third andthe fourth children had a benign course of agranulocytosis which lasted about10 weeks and was followed by spontaneous recovery. A potent leukoagglutininwas found in the maternal serum which agglutinated leukocytes obtained fromthe father and all three available children but failed to agglutinate themother’s own cells. Identical leukoagglutinin was found in the last baby’sserum; it disappeared after the baby recovered. The disorder is tentativelynamed "isoimmune neonatal neutropenia" and is considered to represent acondition analogous to erythroblastosis fetalis.

Submitted on May 4, 1959 Accepted on July 28, 1959