[Homozygous infant in a family with hereditary protein C deficiency]

Blood derived products in pediatrics: New laboratory tools for optimizing potency assignment and reducing side effects

Neonates and children can develop rare bleeding disorders due to congenital/acquired coagulation Factor deficiencies, or allo-immune/autoimmune complications, or can undergo surgeries at high haemorrhagic risk. They then need specialized transfusion of blood components/products, or purified blood extracted products or recombinant proteins. Blood-derived therapies conventionally used for management of affected infants with genetic/acquired deficiencies, bleeding problems (coagulation Factor reduced or missing) or thrombotic disorders (reduced or missing anticoagulant proteins) pose some additional risks. These remedial therapies can cause tolerance when used very early in life and, sometimes needed, repeatedly. The introduction of recombinant proteins has allowed manufacturers to produce large amounts of the proteins usually present at very low concentration in blood. This has also changed the risk pattern of plasma-extracted products, especially in terms of continual reduction of viral transmission. Many efforts have been made over these past decades to reduce the risks associated with the use of all these products in terms of viral and bacterial safety, as well as immune disorders but they are not the objective of this article. Other associated side effects are the presence of undesired activities in blood products, which can produce thrombotic events or adverse reactions. The progressive introduction of blood derived products has greatly improved the prognosis and quality of life of affected patients. This concerns whole blood, but also blood cell concentrates, mainly platelets and red blood cells, plasma, while the blood extracted products are increasingly replaced by recombinant proteins. All these therapeutic products, i.e. blood extracted drugs, improve health and quality of life for hemophiliac's A or B, or patients with auto/allo-immune thrombocytopenias or with rare bleeding disorders, and those with thrombotic events occurring in childhood, which are mainly due to Protein C or Protein S deficiencies (congenital or acquired). Progress in analytical methods and biotechnology allow better control of the manufacturing processes for all blood derived or plasma extracted products and recombinant proteins, and contribute to improved manufacturing processes to minimize the occurrence of side effects. These adverse events can be due to the aging of the blood cell concentrate with release of their granule content, and generation of EVs, which can produce anaphylactic reactions and risk of thrombosis, but also to the presence of activated coagulation Factors in purified products, such as Factor Xia as recently identified in immunoglobulin concentrates. Characterization and measurement of contaminant products is of special usefulness during product preparation and for optimization of manufacturing processes for purified extracted products, but also for recombinant proteins. The pharmaceutical industry introduces these new methods for validating manufacturing processes, or for quality control assessments. The objective is first to warrant the full quality and safety of the lots produced, and assure the highest efficacy with the lowest risks when used in patients. For cell concentrates and fresh blood, storage conditions are critical and measurement of analytes such as EVs or Annexin V allows evaluation of quality of each individual transfused pouch. In addition to all the rules around viral and bacterial transmission risk, and immune tolerance, our available laboratory methods contribute to reducing the side effects of blood cell concentrates and derived plasma products, as well as those of the therapeutic recombinant proteins.

Comparison of different prothrombin complex concentrates--in vitro and in vivo studies

The potency and tests for thrombogenicity were studied prospectively in 7 different (two lots of each brand, A-G) prothrombin complex concentrates (PCC). Human albumine (H) and a factor IX concentrate (I), served as controls. The potency of coagulation factors and inhibitors varied considerably. Two brands (E, F) contained no protein S, additionally one brand contained no protein C. Two preparations exhibited high amidolytic activities, especially towards the thrombin-sensitive chromogenic substrate S-2238, in vitro. These activities could be quenched in part by the addition of hirudin or antithrombin III. The heparin and antithrombin III content of the PCCs was significantly different, and, after addition of antithrombin III an increase of thrombin-antithrombin III complexes in 2 preparations (B, D) was observed in vitro. Additionally, three brands (B, D, F) caused more severe cardio-pulmonary reactions in rabbits, associated with an increase of fibrin split products for brands B and D. We conclude that the use of these preparations in patients, in whom an acquired protein C or S defect, or a hypercoagulable state, can be suspected, cannot be recommended.

Homozygous protein C deficiency in two siblings

Homozygous protein C (PC) deficiency is reported in two siblings (girl and boy) who received their proper diagnoses at the ages of 7 4/12 and 1 3/12 years respectively. The girl had perinatal asphyxia without bleeding. At 1 year of age she developed purpura fulminans. Treatment with heparin and plasma was successful. At 7 4/12 years she developed tender, bluish nonnecrotic skin changes after an orthopedic operation. The PC level was 0.08 U/ml. The boy had had a large intraventricular hemorrhage neonatally and developed severe brain damage. At 1 3/12 years he manifested the same skin changes as his sister and was treated similarly. The PC level was 0.05 U/ml. Both children now receive warfarin continuously and are essentially free of symptoms. The cases represent homozygous phenotypes in a family with a recessive trait of PC deficiency without thrombotic disease. The cases also show that severe PC deficiency may be compatible with life beyond infancy without any specific therapy.

Diagnosis and treatment of homozygous protein C deficiency. Report of the Working Party on Homozygous Protein C Deficiency of the Subcommittee on Protein C and Protein S, International Committee on Thrombosis and Haemostasis

This report summarizes the documented cases of homozygous protein C deficiency in the United States and Europe. Procedures for diagnosing and treating this disorder (both initially and over the long term) have been compiled by a working party on homozygous protein C deficiency of the Subcommittee on Protein C of the International Committee on Thrombosis and Haemostasis. Homozygous protein C deficiency is an autosomal recessive disorder that usually manifests itself by purpura fulminans and, less commonly, by massive large vein thrombosis; severe diffuse intravascular coagulation also develops in these infants, and there is evidence of intrauterine thrombosis. For confirmation of homozygous protein C deficiency in a neonate with purpura fulminans or massive venous thrombosis, the infant should have undetectable protein C activity and both parents should be heterozygous for protein C deficiency. At the onset of symptoms, the initial treatment should be plasma (8 to 12 ml/kg every 12 hours) until all lesions have healed. Two modalities for long-term treatment are accepted as useful in these children: oral anticoagulant therapy or protein C replacement (fresh frozen plasma or prothrombin complex concentrate). Liver transplantation has been performed in only one child, with success. Oral anticoagulation (vitamin K antagonists, maintaining the prothrombin time from one and one-half to two times control values or at the International Normalized Ratio of 2.5 to 4.4) is our recommendation of choice for long-term treatment. With appropriate care, these children are able to be free of coagulopathy and live relatively normal lives.

Heterozygous protein C deficiency type I

Protein C is a vitamin K-dependent plasma protein which has anticoagulatory and profibrinolytic properties as a result of inactivating coagulation factors Va and VIIIa and enhancing fibrinolysis. Heterozygous protein C deficiency is well known to be a risk factor for thromboembolic diseases. We here present a family with 16 members deficient in protein C, out of which only two persons were suffering from thromboembolic disorders. In patients suffering from heterozygous protein C deficiency thromboembolic complications in childhood are rare and are not obligatory in adults. These patients should therefore not be treated with oral anticoagulants unless thromboembolic complications have already occurred or are imminent. Coumarin anticoagulation implicates a serious risk of coumarin skin necrosis in protein C deficient patients during the initial therapeutic phase. This risk may be avoided by initiating coumarin therapy with low doses of the drug and in cases of thromboembolic complications by overlapping with heparin anticoagulation.

Homozygous protein C deficiency with delayed onset of symptoms at 7 to 10 months

We report an inbred family with two cases of homozygous protein C deficiency and review 11 other such cases. Both patients presented in the second half of their first year of life with recurrent rapidly disappearing ecchymotic skin lesions, disseminated intravascular coagulation, and venous thrombosis. Successful treatment has been achieved by frequent infusions of plasma or prothrombin complex then maintained with Warfarin. Homozygous recessive protein C deficiency usually presents in the neonatal period with purpura fulminans. Two cases have been described elsewhere which presented in the second decade of life with milder symptoms. The present cases appear to be intermediate in time of presentation and severity of symptoms. We also review the distinction that is now evident between recessive and dominant protein C deficiency.

Replacement therapy for a homozygous protein C deficiency-state using a concentrate of human protein C and S

A severe congenital deficiency of protein C was diagnosed in a 10-month-old girl who had been suffering from skin necrosis since the age of 7 months. The patient was treated initially with fresh frozen plasma, 10 ml per kg body weight, every 24 h. Following treatment, the mean plasma level of protein C was 0.1 U/ml after 30 min and less than 0.02 U/ml after 24 h. The child was then treated with a concentrate of human protein C and S, 100 U protein C per kg body weight, given every 48 h for a period of 9 months. The mean plasma level of protein C was 0.93 U/ml 30 min after administration of the concentrate and 0.13 and 0.08 U/ml after 24 and 48 h, respectively. The mean post-transfusional in vivo recovery of protein C was 44% and the half life was 8.3 h. The mean plasma level of 'free' protein S increased from 1.1 to 2.2 U/ml after administration of the concentrate. There was no increase in 'bound' protein S. The in vivo recovery of 'free' protein S was 49% and the half life was about 17 h. Since the start of this replacement therapy using a human protein C and S concentrate, the patient has not developed any thromboembolic complications. These results indicate the therapeutic value of human protein C and S concentrate in the treatment of severe protein C deficiency.