Thrombomodulin and ristocetincofactor in homocystinuria: a study in two siblings.

Homocystinuria due to cystathionine-beta-synthase deficiency (CBS-def-HOCY) initially often presents with vascular disorders, e.g. thromboembolic events. The measurement of vascular endothelial markers in plasma could help to assess endothelial damage. We determined von Willebrand factor (measured as Ristocetincofactor, RiCoF) and thrombomodulin (TM), two endothelial cell markers to our knowledge not measured systematically before in homocystinuria patients in a longitudinal study of two homocystinuric patients: Patient1 with thromboembolic disease and his asymptomatic sister, patient2. Before start of therapy in patient 1, TM and RiCoF levels both were increased. In patient 2 a moderately elevated RiCoF and a normal level of TM were found. Vitamin therapy with 15 mg folate and 600 mg pyridoxine per day led to almost complete normalization of amino acids in urine and plasma, and complete normalization of RiCoF and TM levels in both patients. Thus, TM and RiCoF elevations demonstrate that CBS-def-HOCY leads to endothelial cell damage, which resolved under vitamin therapy in the patients studied.

Coagulation factors and markers of activation of coagulation in homocystinuria (HOCY): a study in two siblings.

Homocystinuria due to cystathionine-beta-synthase deficiency (CBS-def-HOCY) initially often present with thromboembolic events. In most cases in which coagulation factors have been analysed, a deficiency of AT-IIIc and factor VIIc has been reported, the cause of which has not been elucidated. Activation of coagulation with consumption of coagulation factors has been postulated as the mechanism. This paper reports a longitudinal study of two patients: patient 1 with thromboembolic disease and his asymptomatic sister, patient 2. Before start of therapy in patient 1, a reduction of FVIIc, other coagulation factors, and AT-IIIc was found. Markers of activation of coagulation (F1 + 2, TAT, FM, D-dimers) were elevated only in patient 1, and only at the time of thrombotic complications. In patient 2 reduced levels of FVIIc and other coagulation proteins, and a low borderline AT-IIIc level was found. Thus, in the two patients, sustained activation of coagulation can be reasonably excluded to be the cause of low levels of coagulation proteins. Vitamin therapy with 15 mg folate and 600 mg pyridoxine per day led to almost complete normalization of amino acids in urine and plasma. Thrombosis has not recurred to date. FVIIc and the other coagulation proteins and AT-IIIc increased in parallel with the biochemical remission. Direct inhibition of the activity of AT-III and coagulation factor VIII and other factors by homocysteine was attempted in vitro but could not be shown at HC concentrations known to occur in the plasma of HOCY patients. Therefore, in these patients, deficient synthesis of coagulation factors and AT-III due to a disturbance of amino acid metabolism is still the most probable explanation for the observed low levels.

Neutrophil granulocytic cell antigen defined by a monoclonal antibody--its distribution within normal haemic and non-haemic tissue.

Monoclonal antibodies were raised against normal human bone marrow cells. One of the antibodies obtained, monoclonal antibody 3C4 (MA 3C4), the subject of this paper, was characterised by immunofluorescence studies with viable normal peripheral blood and bone marrow cells and by immunoperoxidase studies using paraffin sections. In bone marrow and peripheral blood MA 3C4 reacts selectively with cells of late neutrophilic granulopoiesis (myelocytes, metamyelocytes, and neutrophilic granulocytes). Cells of erythropoiesis, thrombopoiesis and lymphopoiesis are negative. In lymph node and spleen only neutrophils react with MA 3C4. In non-haemic tissue reactivity was seen with epithelial cells of a variety of different gland ducts. Thus the antigen detected by MA 3C4 can serve as a marker for neutrophil differentiation in normal haemopoiesis and as a marker for ductal epithelial cells of a variety of organs within non-haemic tissue. The antigen is formalin-resistant and can be detected in paraffin sections. The antibody thus appears to be a valuable reagent for both haematological research and for routine pathology.