Anti-endothelial cell antibodies in patients with various forms of vasculitis.

OBJECTIVE: To determine the prevalence of anti-endothelial cell antibodies (AECA) in various forms of vasculitis and to evaluate their relationships with markers of endothelial cell (EC) injury such as thrombomodulin (TM), von Willebrand factor antigen (vWf) and protein S. METHODS: A total of 167 disease-associated sera, from 79 patients with large- or medium-sized (group I) and 88 with small-sized vessel vasculitis (group II), were examined for the presence of AECA using a cellular enzyme-linked immunosorbent assay (ELISA). These were evaluated before and after incubation with epithelial cells. EC plus epithelial cell (eC) extracts were fractionated and blotted with selected sera, and EC plus mononuclear cell extracts were dotted and blotted with lupus sera. Soluble TM, vWf and protein S levels were measured by ELISA. RESULTS: The binding of antibodies to eC was significant in group II sera (p < 0.01) but not in group I sera, so that the remaining EC-specific activity was significantly higher (p < 0.001) in the latter group than in the former. Eight antigenic specificities appeared to be specific for EC, whereas three were shared with eC. Despite absorption, the sera remained as reactive with EC and MNC as before. Taking the patient group as a whole, the levels of serum TM correlated with the titers of IgG, IgM and IgA AECA. CONCLUSION: EC-specific activity is more often encountered in group I than in group II patients. At present, the explanation for the distinct AECA specificities in these disease associated sera is not clear.

Assessment of activated protein C resistance using a new and rapid venom-based test: STA Staclot APC-R.

Activated protein C (APC) resistance is related to a single point mutation in the factor V gene (FV:Q506) and appears to be the most common inherited risk factor for venous thromboembolism. A reliable screening test is therefore useful. We aimed to evaluate a new APC resistance test, on the basis of the procoagulant activity present in one snake venom of a crotalidae family: STA Staclot APC-R. We studied 36 consecutive patients with an acute deep venous thrombosis (DVT) confirmed by compression ultrasonography and carrying the FV:Q506 allele, assessed by DNA analysis, 103 of their family members and 35 consecutive patients with a proven DVT but who did not carry the FV:Q506 allele. Blood samples were collected within 24 h of admission for the DVT cases and on the day of medical registration for the family members. Tests were performed blind. The STA Staclot APC-R test, using a cut-off value of 0.80, had an overall sensitivity of 100% (95% CI, 95-100) and a specificity of 98.8% (95% CI, 92.0-99.6). An acute thrombosis process did not influence the performance of the test. We conclude that this test is easy and rapid to perform in every day practice and fulfills the criteria for a screening test.

[First contact between blood and the arterial prosthesis. Study of the retention of the blood elements]. / Premier contact sang/prothèse artérielle. Etude de la rétention des éléments sanguins.

In order to characterize the nature of the interaction between arterial prostheses and their initial contact with blood, we propose the use of an in vitro test using labelled platelets and fibrinogen to measure the amount of the thrombotic matrix that is entrapped by the wall of the graft. The results have been confirmed by scanning electron microscopy. Polyester prostheses, whose healing process depends on the reorganisation of the thrombotic matrix, retains considerably more blood cells than the polytetrafluoroethylene microporous prostheses or the treated biological devices, whose fate, following implantation, maintains almost complete passivity.

A case of chronic myelomonocytic leukaemia and factor XI deficiency with a circulating anticoagulant.

Inhibitors against factor XI (FXI) have been frequently described in patients who acquired inhibitors (due to auto-immune disorders, malignancies or infections), but less often in those with a congenital deficiency of this factor, who had received plasma infusions. The present report concerns one such inhibitor found in the plasma of a patient with chronic myelomonocytic leukaemia and infected by B19 parvovirus, who was neither a heterozygote nor a homozygote for FXI deficiency, and who had no bleeding tendency despite a very low FXI level. Taking this case into account, we discuss and present the clinical and biological features of acquired FXI deficiency caused by an inhibitor.

Spontaneous in vitro megakaryocyte colony formation in primary thrombocythemia: relation to platelet factor 4 plasma level and beta-thromboglobulin/platelet factor 4 ratio.

Seventeen patients with primary thrombocythemia (PT) were evaluated for in vitro bone marrow megakaryocyte progenitors (CFU-MK) using a plasma clot system. The aim of this study was to find out whether spontaneous growth of CFU-MK could be used in the diagnosis of PT. The number of CFU-MK was normal in 7 patients and reduced in 10 patients. In the absence of stimulating factor, CFU-MK grew spontaneously in 12 patients, while in 5 patients no spontaneous CFU-MK were observed. The mean plasma level of platelet factor 4 (PF4) was significantly higher (p less than 0.05) in patients without spontaneous CFU-MK (59.8 +/- 59.6 IU/ml; mean +/- SD) compared to patients with (18.1 +/- 20.7 UI/ml). The mean plasma level of beta-thromboglobulin did not differ between patients with or without spontaneous CFU-MK. The beta-thromboglobulin/PF4 ratio was significantly higher (p less than 0.01) in patients with spontaneous CFU-MK (9.9 +/- 7.1) compared to patients without (3.1 +/- 1.4). These results suggest that PF4 could inhibit in vitro spontaneous growth of CFU-MK.