Search results for "Complement system"
showing 10 items of 157 documents
Combined homozygous factor H and heterozygous C2 deficiency in an Italian family
1988
Three of four children in a family have homozygous (less than 1% of normal) deficiency of factor H of the complement system and both parents, who are first cousins, are heterozygous for the same defect. The father and two of the H-deficient siblings also have a partial C2 deficiency. One of the children with combined deficiencies is affected by systemic lupus erythematosus with nephritis. No increased susceptibility to infections has been observed in the family. H deficiency is inherited in an autosomal codominant manner and is independently transmitted from C2 deficiency and HLA haplotypes. In the homozygous state it is associated with very low serum concentrations of B and C3, barely demo…
Additive effects of enhanced ambient ultraviolet B radiation and increased temperature on immune function, growth and physiological condition of juve…
2009
Climate change models predict increased ultraviolet B (UVB) radiation levels due to stratospheric ozone depletion and global warming. In order to study the impact of these two environmental stressors acting simultaneously on the physiology of fish, Atlantic salmon parr were exposed, for 8 weeks in outdoor tanks, to different combinations of UVB radiation (depleted and enhanced) and temperature (standard rearing temperature of 14 °C or 19 °C). The immune function (plasma IgM, lysozyme activity and complement bacteriolytic activity), growth (body weight) and physiological condition (haematocrit and plasma protein concentration) of the fish were determined. Increased UVB level, regardless of w…
Opsonizing activities of IgG, IgM antibodies and the C3b inactivator-cleaved third component of complement in macrophage phagocytosis
1976
Phagocytosis of SRBC by guinea-pig peritoneal macrophages is enhanced by opsonizing IgG antibody alone. IgM antibody requires the presence of bound C3. Treatment of C3b coated SRBC with purified C3b inactivator (yielding EAIgM C1423d) does not reduce attachment to, and phagocytosis by, peritoneal macrophages. This finding suggests the existence of a C3d receptor on peritoneal macrophages. EC43b intermediates which have been produced by removing IgM antibody by mercaptoethanol treatment and by subsequent removal of C1 and C2, are phagocytosed despite the absence of IgM antibody. Furthermore, treatment of EC43b with C3b inactivator does not change phagocytosis. Thus, IgM antibody does not app…
Binding to complement factors and activation of the alternative pathway by Acanthamoeba.
2010
Acanthamoeba can cause severe ocular and cerebral diseases in healthy and immunocompromised individuals, respectively. Activation of complement appears to play an important role in host defence against infection. The exact mechanism, however, is still unclear. The aim of the present study was to investigate the effect of normal human serum (NHS) and normal mouse serum (NMS) on Acanthamoeba trophozoites, the binding of different complement factors to Acanthamoeba and the activation of the complement system. Moreover, we aimed to work out any possible differences between different strains of Acanthamoeba. A virulent T4 strain, a non-virulent T4 strain and a virulent T6 strain were included in…
Secreted proteophosphoglycan of Leishmania mexicana amastigotes activates complement by triggering the mannan binding lectin pathway.
1997
Cutaneous lesions induced by infection of mice with the protozoan parasite, Leishmania mexicana, contain abundant amounts of a high molecular mass proteophosphoglycan (PPG), which is secreted by the amastigote stage residing in phagolysosomes of macrophages and can then be released into the tissue upon rupture of the infected cells. Amastigote PPG forms sausage-shaped but soluble particles and belongs to a novel class of serine-rich proteins that are extensively O-glycosylated by phosphooligosaccharides capped by mannooligosaccharides. The purified molecule is shown here to efficiently activate complement (C) and deplete hemolytic activity of normal serum and may prevent the opsonization of…
The collagen-like component of the complement system, C1q, is recognized by 7 S autoantibodies and is functionally impaired in synovial fluids of pat…
1996
Cross-reactivity between type II collagen (CII) and C1q, the collagen-like subunit of the first component of complement, has been demonstrated in synovial fluid (SF) from rheumatoid arthritis (RA) patients. Many authors have studied autoimmunity to CII in RA, but little work has been done on autoimmunity to C1q in RA. In the data presented here, we have been able to show that in addition to native C1q, an altered form of C1q is present in SF from RA patients. Furthermore, a low molecular weight form of C1q is present in RA SF, although its role, if any, in the pathogenesis of RA is unclear. The presence in these RA SF of C1q-specific antibodies (IgG and IgM) has been studied and we have par…
Complement components in relation to macrophage function
1983
Complement and atherosclerosis—united to the point of no return?
2012
Atherosclerosis is widely regarded as a chronic inflammatory disease that develops as a consequence of entrapment of oxidized low-density lipoprotein (LDL) in the arterial intima and its interaction with components of both innate and adaptive immunity. This article reviews the role of the complement system in the context of a different concept on atherogenesis. Arguments are forwarded in support of the contention that enzymatic and not oxidative modification of LDL is the prerequisite for transforming the lipoprotein into a moiety that is recognized by the innate immune system. In a departure from general wisdom, it is proposed that these processes are initially not pathological. To the con…
Functional analysis of the classical, alternative, and MBL pathways of the complement system: standardization and validation of a simple ELISA.
2004
Primary defence against invading microorganisms depends on a functional innate immune system and the complement system plays a major role in such immunity. Deficiencies in one of the components of the complement system can cause severe and recurrent infections, systemic diseases, such as systemic lupus erythematosus (SLE) and renal disease. Screening for complement deficiencies in the classical or alternative complement pathways has mainly been performed by haemolytic assays. Here, we describe a simple ELISA-based format for the evaluation of three pathways of complement activation. The assays are based on specific coatings for each pathway in combination with specific buffer systems. We ha…
T cell factor (interleukin 2) allows in vivo induction of T helper cells against heterologous erythrocytes in athymic (nu/nu) mice.
1980
Mice carrying the nude mutation (nu/nu) lack a functioning thymus and do not contain detectable levels of immunocompetent T cells. We now report that nu/nu mice do have lymphocytes which can be activated in vivo by heterologous erythrocytes and a Lyt-1 T cell-derived factor (interleukin 2) to generate T helper cells. Thus, a lymphokine is described which is able to restore in vivo T helper cell immunocompetence of nu/nu mice. The data may suggest that nu/nu mice contain a low number of T lymphocytes influenced by the cystic remnant of the nu/nu thymus anlage. Alternatively, the data imply that interleukin 2 circumvents the requirement of a thymus during ontogeny of T lymphocytes.