Deficiency of human complement factor I associated with lowered factor H.

Deficiencies of factor I and/or factor H result in an increased consumption of C3 and higher susceptibility to recurrent infections. Here we describe a case of human factor I deficiency and lowered factor H levels. C3 concentration was 50% lower than normal, the classical pathway-dependent hemolytic activity was reduced to almost 30% of normal, and alternative pathway-dependent activity was completely absent. The killing by peripheral leukocytes of Candida albicans treated with deficient serum and the production of complement-dependent chemotactic factors were reduced in the proband's serum when compared with normal serum. Finally, we observed that C3 antigen present in the proband's serum has a different electrophoretic mobility than native C3 (most likely C3b), confirming the deregulation of complement activation due to the lack of regulatory proteins factors I and H. The impaired complement system described in this case, the first of its kind described in a Chile, explains the higher susceptibility to infections found in the proband.

Bothrops asper snake venom and its metalloproteinase BaP-1 activate the complement system. Role in leucocyte recruitment.

The venom of the snake Bothrops asper, the most important poisonous snake in Central America, evokes an inflammatory response, the mechanisms of which are not well characterized. The objectives of this study were to investigate whether B. asper venom and its purified toxins--phospholipases and metalloproteinase--activate the complement system and the contribution of the effect on leucocyte recruitment. In vitro chemotaxis assays were performed using Boyden's chamber model to investigate the ability of serum incubated with venom and its purified toxins to induce neutrophil migration. The complement consumption by the venom was evaluated using an in vitro haemolytic assay. The importance of complement activation by the venom on neutrophil migration was investigated in vivo by injecting the venom into the peritoneal cavity of C5-deficient mice. Data obtained demonstrated that serum incubated with crude venom and its purified metalloproteinase BaP-1 are able to induce rat neutrophil chemotaxis, probably mediated by agent(s) derived from the complement system. This hypothesis was corroborated by the capacity of the venom to activate this system in vitro. The involvement of C5a in neutrophil chemotaxis induced by venom-activated serum was demonstrated by abolishing migration when neutrophils were pre-incubated with antirat C5a receptor antibody. The relevance of the complement system in in vivo leucocyte mobilization was further demonstrated by the drastic decrease of this response in C5-deficient mice. Pre-incubation of serum with the soluble human recombinant complement receptor type 1 (sCR 1) did not prevent the response induced by the venom, but abolished the migration evoked by metalloproteinase-activated serum. These data show the role of the complement system in bothropic envenomation and the participation of metalloproteinase in the effect. Also, they suggest that the venom may contain other component(s) which can cause direct activation of C5a.

[In vitro effect of bacterial extracts of S. aureus in chemokinesis and chemotaxis of polymorphonuclear cells]. / Efecto in vitro del extracto bacteriano de S. aureus en la quimiocinesis y quimiotaxis de células polimorfonucleares.

The purpose of the study was to determine if the extract of Staphylococcus aureus in vitro can modify chemokinesis and induce chemotaxis of polimorphonuclear (PMN) cells of peripheral blood in healthy donors. Chemocinesis and chemotaxis of PMN of peripheral blood in 30 healthy donors of either sex from 18 to 40 years old was measured. A 5 mL sample of peripheral blood was drawn. PMN were separated by Boyum's method and challenged with of Staphylococcus aureus extract and C5a as chemotactic factors, and Hank's solution chemokinesis. Chemokinesis was 54.6 +/- 8.8 microns, chemotactic response to C5a was 89 +/- 12.5 microns and with bacterial extract the response was 103 +/- 20.1 microns (p). In conclusion, complete extract of Staphylococcus aureus stimulates in vitro chemotaxis of PMN from healthy donors, and this stimulation is similar to known chemotactic factors as C5a.

Production of leukocyte migration inhibition factor (LIF) and migration stimulation factor (MStF) by CD4+ and CD8+ human lymphocytes subsets and T-cell clones.

The production of the lymphokines leukocyte migration inhibition factor (LIF) and migration stimulation factor (MStF) at the level of CD4+ and CD8+ human lymphocyte subsets was investigated. In a first series of experiments, anti-CD4 and anti-CD8 monoclonal antibodies capable of inhibiting the activation by concanavalin-A (Con-A) of the respective T-cell subset were used. It was observed that when CD8+ cell activation was blocked, LIF was always produced after Con-A activation. When CD4+ cell activation was blocked, MStF was produced in five out of nine experiments (no activity in the other four). The addition of N-acetyl-D-glucosamine to block LIF in supernatants of anti-CD8 treated cells was unable to show evidence of masked MStF activity. In a second series of experiments, T-cell clones were established from continuous growing T-lymphocyte cell lines developed from cultures of Con-A activated normal human leukocyte cultures. The phenotype of 22 clones was determined and their ability to produce LIF or MStF investigated. Four clones produced MStF after Con-A activation and all of them were CD3+, CD4-, CD8+. Three clones produced LIF after Con-A activation and all of them were CD3+, CD4+, CD8-. We conclude that LIF is produced by CD4+ cells and MStF by CD8+ cells.

Lymphokine production by blood or spleen mononuclear cells from patients with schistosomiasis mansoni.

Peripheral blood mononuclear cells (PBMN) from individuals with active or former intestinal schistosomiasis mansoni or splenocytes from patients with the hepatosplenic form of the disease were evaluated for their ability to generate chemotactic factors for neutrophils in response to schistosomal antigenic preparations derived from adult worms (SWAP), eggs (SEA), or phytohemagglutinin (PHA). When supernatants from cultures of stimulated PBMN from normal donors were assayed, only those obtained from cells which had been cultured in presence of PHA displayed chemotactic activity for neutrophils. In contrast, supernatants from cultures of SWAP or SEA stimulated PBMN from patients with intestinal or hepatosplenic schistosomiasis were shown to contain chemotactic activity for neutrophils from normal individuals. PBMN from persons who previously had been infected with Schistosoma mansoni but had received chemotherapy years before presented a pattern of response to SWAP or SEA similar to those from patients with active infections. The response of splenocytes from patients with hepatosplenic schistosomiasis was considerably different from PBMN from individuals with active or with treated schistosomiasis. Splenocytes from most of those patients with hepatosplenic disease failed to produce chemotactic factors for neutrophils in response to stimulation with at least 1 of the schistosome antigens tested. These results indicate that the lymphocytes from schistosomiasis mansoni patients are able to recognize and are stimulated by adult worm and egg antigens to produce chemotactic substances for neutrophils, and that this ability persists for many years after chemotherapy with schistosomicidal drugs. At the hepatosplenic stage, immunoregulatory mechanisms, which may prevent the production of chemotactic factors by splenocytes and/or their activity upon neutrophils in vitro, seem to occur.

Macrophages stimulated with lipopolysaccharide release a selective neutrophil chemotactic factor: an in vivo demonstration.

Intraperitoneal injection of a chemotactic factor released by macrophage monolayers preincubated with endotoxin induced the migration of neutrophils but not of macrophages into the abdominal cavity of rats, whereas injection of carrageenin, thioglycolate or endotoxin stimulated the migration of both types of cells.

PMN chemotactic factor produced by glass-adherent cells in the acute inflammation caused by Paracoccidioides brasiliensis.

Intraperitoneal inoculation of BIO.A mice with P. brasiliensis induces an acute inflammatory infiltrate in which 40-50% of the cells are PMN leucocytes. Previous depletion of serotonin, prostaglandin, histamine and complement does not alter the course of inflammation. Complement-derived factors appear to have no active participation in the process since C5-deficient mice depleted or not by Cobra venom factor (CoF) show the same kind of cellular influx. On the other hand, peritoneal cells incubated (6 h) with the fungus release a soluble factor that induces in vivo an active chemotaxis of PMN cells when inoculated i.p. The factor has the following characteristics: a) it is produced by adherent cells; b) it is protein in nature; c) its production is inhibited by incubation of peritoneal cells with 10 micrograms/ml puromycin and d) it has a molecular weight less than 15 000 daltons, as determined by gel filtration through a Sephadex G-75 column.

Regulation of eosinophilia in rats infected with Nippostrongylus brasiliensis. I. Eosinophil chemotactic factor produced spontaneously by mesenteric lymph node cells of infected rats.

The possible mechanism of eosinophilia was studied in rats undergoing primary infection with Nippostrongylus brasiliensis (Nb). In vivo studies showed that the kinetics of intestinal tissue eosinophilia was not directly related to those of the intestinal worm burden. Furthermore, Nb worm extract has no or only very weak in vitro eosinophil chemotactic activity, suggesting that parasite-derived eosinophil chemotactic factor (ECF) is, if at all, not a major regulator for intestinal tissue eosinophilia in this Nb rat system. On the other hand, when mesenteric lymph node (MLN) cells obtained various days after infection were cultured, potent ECF activity was detected in the cell-free supernatant from the cultures of MLN cells 15-20 days after infection, at which time marked intestinal tissue eosinophilia was observed in vivo. Production of ECF by MLN cells from Nb-infected rats seems to be spontaneous, since these cultures were performed without adding worm antigen. ECF-producing activity of day-20 MLN cells was suppressed by adding various metabolic inhibitors such as cycloheximide, mitomycin C, or puromycin. After Sephadex G-75 gel filtration, ECF activity produced by day-20 MLN cells was associated with two different molecules.