C1 inhibitor and diagnosis of hereditary angioedema in newborns

Hereditary and acquired angioedema: problems and progress: proceedings of the third C1 esterase inhibitor deficiency workshop and beyond

Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

Clinical management of hereditary angio-oedema in children

Hereditary angio-oedema (HAE) results from the deficiency of C1-esterase inhibitor (C1-INH). The clinical picture of this autosomal dominant disorder is characterized by recurrent attacks of subcutaneous oedema and/or potentially life-threatening swelling of the submucosa. This review discusses the authors' decade-long experience obtained in the treatment and follow-up of pediatric patients with HAE. Twenty-six children with HAE were reviewed. Pedigree analysis was performed in all cases to identify afflicted relatives. C1-INH concentrate was reserved for the emergency treatment of acute oedematous attacks, whereas tranexamic acid and danazol were administered for short- or long-term prophylaxis. Follow-up care included laboratory tests and abdominal ultrasound, which was repeated at regular intervals. Twenty-one children had Type I HAE and five suffered from Type II HAE. Clinical manifestations of the disease first occured in children when 2.5-12 years of age. Oedema formation primarily afflicted subcutaneous tissues. Mechanical trauma was identified as a precipitating factor in 20 patients. Pedigree analysis revealed 24 patients with relatives who suffered from HAE. Long-term prophylaxis with tranexamic acid or danazol was initiated in 11 patients; two children required short-term prophylaxis. No drug-related adverse effects were observed, except for one case of delayed menarche. Therapy improved serum complement parameters significantly and substantially reduced the frequency and severity of clinical episodes. Adequate prophylaxis and follow-up care can spare pediatric patients from oedematous attacks caused by HAE. Undesirable adverse effects can be avoided and the patient's quality of life enhanced considerably by administering the lowest effective drug dose.

Current management of hereditary angio-oedema (C'1 esterase inhibitor deficiency)

Hereditary angio-oedema is characterised by recurrent swellings in any part of the body and also by recurrent attacks of severe abdominal pain. The disease is inherited in an autosomal dominant manner but up to 25% of cases can occur as a spontaneous mutation. Attacks of swelling can be precipitated by trauma, certain drugs, and emotional stress. Treatment usually involves a combination of prophylaxis, using androgens or antifibrolytic drugs, and replacement with C'1 esterase inhibitor concentrate for acute attacks and before surgery or other traumatic procedures.

Acute phase haemolysis in chronic cold agglutinin disease

We previously described a paradoxical form of chronic cold agglutinin disease (CAD) in which haemolysis occurred during episodes of fever but only marginally during exposure to colds. In order to investigate the molecular basis for this response we performed a 12-month prospective study of a patient with CAD and paradoxical haemolysis. Blood samples were collected monthly during health, and daily following hospitalization owing to hip fracture. During health we observed decreased levels of C3, undetectable C4, a non-functional classical pathway and a normal alternative pathway. Increased concentrations of C1-INH/C1rs complexes indicated continuous formation of C1-antibody-antigen complexes. There was a low-grade temperature-dependent fluctuating haemolysis as evidenced from measurements of lactate dehydrogenase. Following the hip fracture, the haemolysis increased. Levels of interleukin (IL)-1beta, IL-6, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha increased as did C1-INH, C3, C4, CRP, and lactate dehydrogenase. The results support our hypothesis stating that paradoxical haemolysis in CAD is controlled by the availability of early classical pathway complement molecules and that haemolysis following acute phase responses occurs as a consequence of increased complement synthesis.

Angio-oedema in a neonate with IgG antibodies to parvovirus B19 following intrauterine parvovirus B19 infection

We report a neonate with angio-oedema following fetal hydrops caused by maternal parvovirus B19 infection. Levels of complement components, including total haemolytic complement activity and C1 inhibitor concentration, were within normal ranges in cord blood. Neonatal angio-oedema might be included in the clinical spectrum of parvovirus B19 infection in pregnancy.

Immunoglobulin prolongs survival of pig kidneys perfused ex vivo with human blood

Intravenous immunoglobulin (IVIG) (Octagam), was used to determine the effect on hyperacute rejection in an ex vivo xenograft model. Six pig kidneys were perfused with IVIG and fresh human AB blood, and six control pig kidneys were simultaneously perfused with albumin and blood from the same donation. The survival of the IVIG-perfused xenografts (median, 6.5 h) was significantly (P = 0.03) longer than the albumin-perfused xenografts (median, 3.5 h). Complement was activated in both groups. The administration of IVIG to the perfused blood resulted in immediate and significantly higher complement activation in the fluid phase as compared with the albumin group. At rejection the fluid phase complement activation was higher in the IVIG group than in the albumin group for C1rs/C1inh complexes, C4bc, Bb and TCC. At the time of rejection both the albumin and the IVIG group demonstrated interstitial tubular haemorrhage, vasculitis or necrosis of glomerular capillaries and glomerular microthrombi. IgM, C1q, C3c, C4 and fibrin were located in arteries and glomeruli and IgG in the interstitium in both groups at rejection. The fluid phase findings are consistent with a modulatory effect of IVIG on complement activation by deviating the classical pathway activation towards the fluid phase. The prolonged survival of the IVIG-perfused kidneys suggests that IVIG may be useful to dampen hyperacute rejection.

Identification of a C-->T mutation in the reactive-site coding region of the C1-inhibitor gene and its detection by an improved mutation-specific polymerase chain reaction method

Mutations in the C1-inhibitor (C1-INH) gene, leading to low functional levels of C1-inhibitor protein, cause hereditary angioedema (HAE). The disease is characterized by episodic edema in a number of organs. Typically, swellings occur in extremities and face, often accompanied by crampy abdominal pain. Laryngeal edema may lead to suffocation. Type II HAE patients have low functional C1-INH values stemming from only one normal allele. Antigenic C1-INH values, however, are normal or increased owing to the presence of a dysfunctional protein from the mutated allele. The mutations are usually found in exon 8 coding for the amino acids near the reactive centre (P1). Previously, no mutations in the C1-INH gene had been published from the Scandinavian countries. In this work, exon 8 of the C1-inhibitor gene was sequenced in members of two different kindreds, from western and northern Norway, who were suffering from HAE type II. A common point mutation was found within the bait region encoding the reactive centre. The codon CGC was converted to TGC at position 17970, corresponding to an Arg-->Cys replacement which reportedly is the second most frequent type II HAE mutation. This information was utilized to develop a mutation-specific polymerase chain reaction (PCR) for the identification of affected family members. The antisense 17-mer primer (5'-AAGACCAGCAGGGTGCA-3') was successfully applied and AmpliTaq Gold was used in the PCR.

Vaccination against middle-ear bacterial and viral pathogens

Considerable evidence suggests that otitis media (OM) can be prevented by systemic immunization. Building on the highly effective H. influenzae type b (Hib) conjugate vaccine technology, pneumococcal conjugate vaccines are being developed to circumvent T-independence of these antigens and provide durable immunity at a very young age. Several pneumococcal conjugate vaccines are currently in clinical testing. Potential vaccine antigens of nontypable H. influenzae (NTHi) include OMP, HMW, pili, and fimbriae. Several OMPs show extensive homology among strains, but surface, determinants of others are highly variable so that antibodies to surface epitopes of one strain will not bind to surface epitopes of another. Several M. catarrhalis OMP and HMW antigens have vaccine potential, but no functional correlates of protection have been identified, and there is no clear evidence that antibody to M. catarrhalis is associated with OM protection. Attenuated viral vaccines also hold promise of preventing childhood OM. Two clinical trials with killed influenza vaccines have shown a significant reduction in OM among vaccine recipients compared to control children during periods of high influenza disease activity in the community. Passive immunoprophylaxis also has potential for preventing OM. Human bacterial polysaccharide immune globulin was protective for pneumococcal OM in children and in the chinchilla OM model. High-dose respiratory syncytial virus-enriched immunoglobulin reduced the incidence and severity of RSV lower respiratory tract infection in high-risk children. Passive immunoprophylaxis may also be effective in children with specific immune deficiencies, such as IgG2 deficiency, and patients who fail to respond to vaccines.

Cleavage of plasma high molecular weight kininogen in surgical ICU patients

OBJECTIVE

To characterize kininogens in plasma from surgical patients in the intensive care unit (ICU).

DESIGN

Prospective study.

SETTING

Surgical ICU.

PATIENTS

35 patients aged 19-79 years, divided into two groups: sepsis (defined by standard criteria) and nonsepsis.

MEASUREMENTS AND RESULTS

Studies of proteolytic degradation of H-kininogen showed degradation in both patient groups compared to healthy controls. Functional quantification of prekallikrein showed a reduction of prekallikrein in plasma from both patients groups. Functional quantification of kininogens by a cysteine proteinase inhibitor assay showed no significant differences between the patients and the controls. Immunological levels of H-kininogen and total kininogen were not significantly different from normal plasma. No differences could be detected between the two patient groups in any of the parameters studied.

CONCLUSIONS

This study showed that contact activation took place in surgical ICU patients: partial kinin release and consumption of prekallikrein took place in vivo.