Prothrombin Quick. A newly identified dysprothrombinemia

The rarest of reported inherited plasmatic coagulopathies involve prothrombin. Only 10 families with significant reductions of this plasma protein (hypoprothrombinemia) have been observed. Even fewer, six families, have been found to have a functionally abnormal prothrombin (dysprothrombinemia) in their blood. An as yet undefined prothrombin abnormally has been recognized in eight other families. One of the first patients previously identified by Quick and his associates as having a defect in her plasma prothrombin has been shown to have about half the normal amount of prothrombin antigen but virtually no prothrombic function. We propose that this dysprothrombin be designated prothrombin Quick. An additional patient also first described by Quick was found to be truly hypoprothrombinemic--that is, to lack both functional and antigenic prothrombin. Briefly summarized are the other five families with dysprothrombinemia, nine with hypoprothrombinemia, and the eight in whom the defect has not been classified.     

STUDIES ON THE DIFFERENTIATION OF THYMUS-DERIVED LYMPHOCYTES

The development pathway from embryonic thymus-stem cell to peripheral thymus-derived lymphocyte has been demonstrated using the alloantigens θ (theta) and TL as surface markers of cell differentiation. On the basis of cytotoxicity tests carried out on CBA.H or A embryo thymus cultured in diffusion chambers and on CBA.H embryo thymus grafts and peripheral lymphocytes derived from them in AKR hosts, it has been concluded that two differentiation stages take place during the maturation of thymus-derived cells, namely a first step from stem cell to thymocyte and a second step from thymocyte to peripheral lymphocyte.