No association of IL2, IL4, IL6, TNF, and IFNG gene polymorphisms was found with Taenia solium human infection or neurocysticercosis severity in a family-based study

Neurocysticercosis (NC) is caused by the establishment of the metacestode stage of Taenia solium in the human central nervous system. A great heterogeneity in the susceptibility to the infection and to the disease has been reported. While the factors involved in this heterogeneity are not completely understood, clearly different immune-inflammatory profiles have been associated to each condition. This study evaluated the association of cytokine single nucleotide polymorphisms (SNPs) with susceptibility to infection and disease severity in NC patients. Blood samples from 92 NC cases and their parents (trios) were genotyped for SNPs in five cytokines relevant for the immune response: IL4 (-589C/T), IL6 (-174C/G), IFNG (+874T/A), TNF (-238G/A), and IL2 (-330G/T). Specific DNA fragments were amplified by the polymerase chain reaction, using the 5'-nuclease Taqman assay on a 7500 platform, allowing the detection of the polymorphism genotypes. No association between the polymorphisms evaluated neither with susceptibility to infection nor with disease severity was found, although previous studies reported variations in the levels of these cytokines among different NC clinical pictures. These results, nevertheless, add new elements to our understanding of the complex pathogenic mechanisms involved in susceptibility to infection by T. solium cysticerci and the severity of the ensuing disease.

Genetic analysis of human predisposition to hepatosplenic disease caused by schistosomes reveals the crucial role of connective tissue growth factor in rapid progression to severe hepatic fibrosis

Schistosome worms inhabit mammalian mesenteric veins. Their eggs cause chronic inflammation, which progresses to periportal fibrosis in 5 to 30% of cases, increasing portal blood pressure and leading to esophageal varices. Episodes of bleeding cause hepatic necrosis and may ultimately lead to hepatic failure and the death of the patient. Schistosome infections can also cause pulmonary hypertension and heart failure. The mechanisms of fibrogenesis and fibrolysis are beginning to be unraveled, but it remains unclear why disease occurs only in certain subjects, as also observed for other types of chronic liver inflammation, as in hepatitis C or B. We summarize here the results that showed that fibrosis progression is determined by a genetic locus on chromosome 6. The CCN2 gene at this locus, encodes CTGF that is a crucial regulator of fibrosis. Two groups of CCN2 polymorphisms independently modulate the progression of hepatic fibrosis. These results were obtained in an Asian population, but were extended to humans living in Africa and South America and are presently tested in liver fibrosis of other etiological origins.

Implication de l'interleukine 13 et de son récepteur dans la sclérodermie systémique

PURPOSE

Interleukin 13 is an immunoregulatory cytokine predominantly secreted by activated Th2 cells. It has similar functions with interleukin 4 and they share a common receptor. However, unlike interleukin 4, l'interleukin 13 does not appear to be important in the initial differentiation of CD4 T into Th2-type cells, but rather appears to be necessary in the effector phase of inflammation and fibrosis. This cytokine has been involved in recent works in allergic inflammation and in some fibrotic diseases leading to a scientific interest to analysis the role of interleukin 13 in systemic sclerosis (scleroderma).

MAIN POINTS

Systemic sclerosis is an autoimmune disease characterized by vascular alteration and skin and visceral fibrosis. A genetic background associated with susceptibility is supposed. Knowing the profibrogenic properties of interleukin 13, we asked if polymorphisms located in interleukin 13 and interleukin 13 receptor genes could be associated with systemic sclerosis. We observed significant associations between IL13 and IL13RA2 gene polymorphisms and the disease, particularly the cutaneous diffuse form of the disease.

PERSPECTIVES AND PROJECTS

Results concerning the involvement of interleukin 13 pathway in systemic sclerosis need to be confirmed on another larger population. Functional studies will be done to explain the effect of these associations. We feel that IL13/IL13R pathway is interesting as immunomodulation with the interleukin 13 receptor inhibitor is possible in therapy.

An epidemiological study of familial neurocysticercosis in an endemic Mexican community

Neurocysticercosis (NC) caused by Taenia solium is a frequent parasitic disease of the central nervous system. It is highly endemic in many developing countries, where many people are exposed but few become infected. Here, the relevance of age, gender, and genetic and exposure factors on NC susceptibility was studied in 649 inhabitants of a rural community of Mexico. Endemicity was confirmed by the high prevalence of pig cysticercosis (32.8%) and human seroprevalence (43.8%). Human NC cases were diagnosed by computerised tomography scans. A questionnaire to evaluate risk factors was applied and familial relationships between participants were registered. An overall NC frequency of 9.1% (59/649) was found. NC frequency increased with age but did not associate with gender. Most NC cases were asymptomatic. None of the evaluated risk factors were associated with NC. No familial aggregation was detected when studying all cases, although a significant relationship between mother and child in cases with multiple parasites was found. These findings point to the fact that human NC in high exposure conditions is not simply related to exposure factors and they do not support the participation of a major gene in single-cyst NC. Rather, our results point to a complex interaction of genetic and environmental factors involved in NC.

Facteurs de prédisposition génétiques à la fibrose au cours de la sclérodermie systémique

PURPOSE

Physiopathology of systemic sclerosis includes autoimmunity factors, endothelial lesions and abnormal fibrotic process which characterizes this disease in the field of systemic autoimmune disorders. Genetic factors of susceptibility are showed by possibility of familial forms of the disease, Choctaw American Indians homogenous population with high disease prevalence of systemic sclerosis and experimental animal models.

KEY POINTS

We propose a review of the articles published to date in the literature concerning genetical analysis of genes coding for factors potentially involved in the fibrotic process of systemic sclerosis. This includes cytokines (TNF-alpha, interleukin-1, chemokines), growth factors (TGF-beta), extracellular matrix proteins (collagen, fibrillin, fibronectine) and agents acting on vascular tone (angiotensin-converting enzyme and NO synthase).

PERSPECTIVES

Identification of genetic factors involved in the susceptibility to fibrosis of systemic sclerosis would lead to a better understanding of physiopathological mechanisms of this disease and to therapeutic targets using immunomodulation with drugs, such as already performed in rheumatoid arthritis.

High prevalence of calcified silent neurocysticercosis in a rural village of Mexico

Human neurocysticercosis (NC) is a parasitic disease caused by TAENIA SOLIUM when its larvae lodge in the central nervous system. NC prevalence estimates are obscured by the variable and often asymptomatic clinical picture. While infection depends on exposure, severity is possibly related with various host factors (immunity, genes and gender). This epidemiological study of cranial CT scans in an endemic rural community found that 9.1% of apparently healthy subjects had calcified lesions and were completely asymptomatic. Silent NC cases did not correlate with the exposure factors tested but showed family aggregation and higher rates of positive serology. Thus, NC prevalence may be higher than currently considered and host-related factors appear to be involved in infection and pathogenesis.

Genetic control of visceral leishmaniasis in a Sudanese population: candidate gene testing indicates a linkage to the NRAMP1 region

There is some evidence showing that genetic factors are involved in human susceptibility to parasitic diseases such as schistosomiasis and malaria. Studies have shown that the Nramp1 and H-2 genes are implicated in the control of Leishmania donovani infection in mice. We sought genetic loci involved in the control of susceptibility to visceral disease caused by L. donovani in humans. We studied 37 families with at least two affected sibs living in a village in eastern Sudan, where an outbreak of visceral leishmaniasis occurred between 1995 and 2000. The genetic markers located in five chromosomal regions containing candidate genes were typed: 2q35 (NRAMP1), 5q31-q33 (Th2 cytokine cluster), 6p21 (HLA/TNF-alpha), 6q23 (INFGRI) and 12q15 (INF-gamma). Linkage (multipoint lod-score=1.08; P=0.01) was observed for the 5'(CA) repeat polymorphism in the NRAMP1 promoter. This suggests that genetic variations of this gene affect susceptibility to visceral leishmaniasis in this population.

The sandfly fauna in the visceral-leishmaniasis focus of Gedaref, in the Atbara-River area of eastern Sudan

Visceral leishmaniasis (VL) is an acute public-health problem in Sudan. Between 1997 and 2000, four, brief entomological surveys were carried out in Barbar El Fugarra, a village in the state of Gedaref, in the Atbara-River area of eastern Sudan. Between 1996 and 1999, 658 cases of VL occurred among the village's population of about 4000. CDC miniature light-traps set inside and outside human dwellings were used to collect a total of 12,745 sandflies, including five species of the genus Phlebotomus and 19 of Sergentomyia. Phlebotomus papatasi and P. orientalis made up 7% and 5% of the collected sandflies, respectively. Seasonal variation was observed in the numbers of P. orientalis, P. papatasi, S. schwetzi and S. magna caught. Almost all (88%) of the sandflies collected were caught inside houses or granaries and there appeared to be particularly large indoor populations of P. orientalis, P. papatasi, S. schwetzi, S. magna and S. clydei. Phlebotomus orientalis could be responsible for the indoor transmission of the parasites causing the local VL, between humans and between humans and local dogs (which have been found infected by some of the Leishmania zymodemes found in humans). The co-occurrence in this focus of P. papatasi and Arvicanthis niloticus, which are known vectors and reservoir hosts, respectively, of L. major, indicates the possibility that outbreaks of human cutaneous leishmaniasis might occur in the area.

Five-year impact of repeated praziquantel treatment on subclinical morbidity due to Schistosoma japonicum in China

We report the 5-year impact (1996-2001) of repeated praziquantel chemotherapy on subclinical morbidity related to Schistosoma japonicum infection. We repeated stool examinations and hepatosplenic ultrasonography in a cohort of 120 individuals living on an island with endemic infection in Dongting Lake, China. Prevalence of schistosome infection fell by 43% and intensity (geometric mean eggs per gram) declined by 80% over the 5 years. However, transmission persisted at a dangerously high rate of 13% per year for re-infection or new infection in the cohort. The prevalence of left-lobe enlargement and dilated portal vein fell significantly (P < 0.01) to about half initial levels although a few patients progressed during the study period. At study endpoint, infection was nearly twice as common if the portal vein was dilated (23% versus 13%, respectively), but this association was not statistically significant (P > 0.05). However, endpoint infection was even more strongly associated with left-lobe enlargement (57% versus 15%, P < 0.01). The proportions of subjects with improved parenchymal and periportal fibrosis were much higher than the proportions of subjects that progressed (P < 0.05). Reduction of prevalence and intensity of infection, and improvement of subclinical morbidity, were benefits of repeated treatments. Further research is needed to understand why some patients developed fibrosis despite substantial reductions in egg counts and to evaluate the functional importance of residual subclinical morbidity after chemotherapy-based control in the lake and marshland area of China.

Description of three new polymorphisms in the intronic and 3'UTR regions of the human interferon gamma gene

Interferon-gamma (IFN-gamma) is a key regulator of the development and functions of the immune system. In particular, this cytokine plays a major role in immune defense against infections by various human pathogens and polymorphisms in the IFN-gamma gene, including the transcription regulatory region, and might affect host resistance to infectious agents such as schistosomes. In this study on the genetics of human schistosomiasis we uncovered three new single nucleotide polymorphisms in the IFN-gamma genes. Two polymorphisms are located in the third intron and the third is in the 3'UTR region of this gene: an A to G transition at position +2109 from the transcription start and two G to A transitions at positions +3810 and +5134. In a SUDANESE population living in an endemic area of malaria and schistosomiasis, the allelic frequenciesare: 0.85 (+2109A), 0.15 (+2109G), 0.92 (+3810G), 0.08 (+3810A), (+5134G) and 0.04 (+5134A).

Two new polymorphisms in the human interferon gamma (IFN-gamma) promoter

Two new single-nucleotide polymorphisms are described within the human interferon gamma (IFN-gamma) promoter in a Sudanese population. One is a G to T transition at position -183 from the transcription start. The other is a A to G transition at position -155. Allelic frequency analysis indicated frequencies of 0.927 (G) and 0.073 (T) at position -183 and 0.977 (A) and 0.023 (G) at position -155. These two polymorphisms have not been detected in the Centre d'Etude du Polymorphisme Humain (CEPH) reference population. The polymorphism -183(G-->T) may alter the AP-1 binding domain and the regulation of transcription. The polymorphism -155(A-->G) is located close to the nuclear factor-activated T-cell site (NFAT site) (-168 TAAAGGAAA-160) and may affect the stability of this region.

[Schistosoma mansoni schistosomiasis]

Schistosomosis are parasitic diseases caused by blood flukes of the Schistosoma genus. The pathology of schistosomosis is mostly brought about by ova trapped in the tissues. In the liver, granuloma around ova eventually trigger periportal fibrosis and portal hypertension. In S. mansoni infection, the infection intensity and the onset of liver fibrosis are under distinct genetic control. Liver fibrosis is the main cause of death in the 20 millions individuals suffering from chronic schistosomosis. However, liver fibrosis is reversible if antischistosomal drugs are administered before the onset of severe hepatic insufficiency.

Genome search for additional human loci controlling infection levels by Schistosoma mansoni

Schistosomiasis is a major public health problem in many developing countries. Previous studies have shown that infection levels by Schistosoma mansoni in a Brazilian population is controlled by a major gene, denoted as SM1, which was mapped to chromosome 5q31-q33 by use of a model-based (logarithm of the odds [lod] score) analysis method. The present study is an autosome-wide scan searching for additional human loci implicated in the regulation of S. mansoni infection intensities. The weighted pairwise correlation model-free linkage method was used in order to consider large pedigrees and to conduct a 2-locus analysis (i.e., to search for a second locus taking into account linkage to 5q31-q33). The most significant linkage results were again obtained in the 5q31-q33 region. Two additional regions provided linkage results with significance levels around 0.001, 1p21-q23 (results independent of 5q31-q33) and 6p21-q21 (results in interaction with 5q31-q33). The investigation of these regions, which contain some candidate genes, is ongoing in other populations to confirm the role of these regions.

Sudan: the possible original focus of visceral leishmaniasis

Fifty-two Leishmania strains, obtained from human patients and dogs in a visceral leishmaniasis focus in Sudan, were characterized by isoenzyme electrophoresis (15 enzymes). The phylogenetic analysis showed that the 7 Leishmania zymodemes obtained hold ancestral positions on the phylogenetic tree, supporting the hypothesis of an East African origin of visceral leishmaniasis.

[Genetic predisposition to bilharziasis in humans: research methods and application to the study of Schistosoma mansoni infection]

The development of genetic epidemiology methods using recent human genetic mapping information together with the growing availability of candidate genes has led to major advances in the identification of host genes in human schistosomiasis. Two phenotypes have been studied so far in the infection by Schistosoma mansoni: infection levels by the parasite as measured by the faecal egg counts, and the severe hepatic fibrosis caused by S. mansoni assessed by ultrasound examination. The first study was performed on Brazilian pedigrees and provided strong evidence for a major gene controlling infection levels by S. mansoni denoted as SM1 which was mapped to chromosome 5q31-q33. This region contains several candidate genes involved in the regulation of the Th1/Th2 response, and the direct role of polymorphisms located within these genes is under investigation. The second study conducted in Sudan also showed the presence of a major gene influencing the development of severe hepatic fibrosis due to S. mansoni infection denoted as SM2. This gene is not located in the 5q31-q33 region, but maps to chromosome 6q22-q23 and is closely linked to the IFN-gamma R1 gene encoding the receptor of the strongly anti-fibrogenic cytokine Interferon-gamma. These findings indicate that two distinct genetic loci control human predisposition to schistosomiasis, SM1 located in the 5q31-q33 region which is likely to play a role in the Th1/Th2 differentiation, and SM2 in 6q22-q23 influencing disease progression with a possible involvement in the regulation of IFN-gamma.

[Diagnostic approach to hypereosinophilia]

Blood hypereosinophilia is a common finding in medical practice requiring further investigation. There are a wide range of potential causes including atopic disorder, drug allergy, parasitic infection, certain forms of immune deficiency, inflammatory process, hemopathy, and malignant disease. Diagnosis of persistent hypereosinophilia not associated with parasitic infection is one of the major diagnostic dilemmas in medicine. If through investigation fails to achieve diagnosis, idiopathic hypereosinophilia may be suspected including the possibility of essential hypereosinophilic syndrome or Chusid syndrome. The primary determination for diagnosis of hypereosinophilia involves the presence or absence of parasitic infection. If parasitic infection is ruled out, it is often difficult to distinguish benign, self-limiting forms from severe forms requiring careful surveillance and subsequent treatment. From a pathophysiological standpoint, one may ask if some eosinophilic conditions are not due to deregulation of immunologic mechanisms that normally protect the organism against parasitic infection.

[Genetic control of hypereosinophilias]

Polynuclear eosinophils play a major role in host defense against infectious diseases and especially helminthiasis. Onset of hypereosinophilia can be attributed to two mechanisms which can occur separately or in combination. The first mechanism involves enhancement of medullary production and differentiation of eosinophils. The second is prolonged life span of eosinophils. Response to eosinophils depends on various cytokines including IL-5, IL-4, IL-3 and GM-CSF. Since it contains the genes coding for these cytokines, the 5q31-q33 region of chromosome 5 is the focus of study on genetic control of human hypereosinophilia. The goal of these studies is to allow screening of subjects predisposed to helminthic infection and to deregulation of immune responses that may lead to atopy and various types systemic inflammatory diseases.

Full results of the genome-wide scan which localises a locus controlling the intensity of infection by Schistosoma mansoni on chromosome 5q31-q33

Three hundred million individuals are at risk of infection by schistosomes, and thousands die each year of severe hepatic disease. Previous studies have shown that the intensity of infection by Schistosoma mansoni in a Brazilian population is controlled by a major gene, denoted as SM1. We report here the full results of a genome-wide search that was performed on this population to localise SM1. Two hundred and forty-six microsatellites were used for the primary map, and only one region in 5q31-q33 provided significant evidence of linkage. SM1 was subsequently mapped to this region, which contains several genes encoding cytokines or cytokine receptors which are involved in protection against schistosomes. Three additional regions, 1p22.2, 7q36 and 21q22-22-qter, yielded promising, although not significant, lod-score values. These regions contain candidate genes encoding cytokines or molecules relevant to anti-schistosome immunity.

Absence of linkage between MHC and a gene involved in susceptibility to human schistosomiasis

Six hundred million people are at risk of infection by Schistosoma mansoni. MHC haplotypes have been reported to segregate with susceptibility to schistosomiasis in murine models. In humans, a major gene related to susceptibility/resistance to infection by S. mansoni (SM1) and displaying the mean fecal egg count as phenotype was detected by segregation analysis. This gene displayed a codominant mode of inheritance with an estimated frequency of 0.20-0.25 for the deleterious allele and accounted for more than 50% of the variance of infection levels. To determine if the SM1 gene segregates with the human MHC chromosomal region, we performed a linkage study by the lod score method. We typed for HLA-A, B, C, DR and DQ antigens in 11 informative families from an endemic area for schistosomiasis in Bahia, Brazil, by the microlymphocytotoxicity technique. HLA-DR typing by the polymerase chain reaction with sequence-specific primers (PCR-SSP) and HLA-DQ were confirmed by PCR-sequence-specific oligonucleotide probes (PCR-SSOP). The lod scores for the different theta values obtained clearly indicate that there is no physical linkage between HLA and SM1 genes. Thus, susceptibility or resistance to schistosomiasis, as defined by mean fecal egg count, is not primarily dependent on the host's HLA profile. However, if the HLA molecule plays an important role in specific immune responses to S. mansoni, this may involve the development of the different clinical aspects of the disease such as granuloma formation and development of hepatosplenomegaly.

[Genetic predisposition to infectious diseases]

At the present time more is known about barriers to transmission of infectious agents between species than barriers to transmission within the same species. However differences in resistance to infection have been well-established within given species of various plants and domestic farm animals. Unsurprisingly several similar mechanisms have been observed in humans. A well-known human example of genetic protection is resistance to malaria in endemic areas which has been associated with polymorphism in alpha and beta chain globulin genes, cytoskeleton proteins, and protein/receptors on the surface of red blood cells. Studies regarding infection by Schistosoma mansoni show that the extent of infection depends largely on each individual's intrinsic resistance under the control of a single major gene which has now been located on q31-33 locus of the long arm of chromosome 5. This locus harbors several genes involved in differentiation of auxiliary T lymphocytes. With regard to HIV infection it has been known for several years that a small but significant number of individuals are relatively resistant. This resistance has been attributed to deletion of the gene coding for the chemokine receptor used by the virus as a co-receptor to infect macrophage.

Evidence for the segregation of a major gene in human susceptibility/resistance to infection by Schistosoma mansoni

Severe clinical disease caused by the major human parasite Schistosoma mansoni is the consequence of high and prolonged infections. Epidemiological studies indicate that, for individuals having frequent contacts with cercaria-infested waters, both infection intensities and reinfection after treatment depend, in large part, on their intrinsic susceptibility/resistance to infection, suggesting the role of genetic factors in human resistance to S. mansoni. To investigate whether a major gene controls human susceptibility/resistance to infection by S. mansoni, segregation analysis of infection intensities, adjusted for the factors relevant in schistosomiasis (water contact, age, sex), was performed on 20 Brazilian pedigrees (269 individuals), using both the unified mixed model and the regressive model of analysis. The results are consistent with the hypothesis that there is a codominant major gene controlling human susceptibility/resistance to infection by S. mansoni. Parameter estimates indicate a frequency of .20-.25 for the deleterious allele; thus, about 5% of the population is predisposed to high infections, 60% is resistant, and 35% has an intermediate, although fairly good, level of resistance. These findings provide a genetic basis for earlier observations on the lower resistance and the predisposition to reinfection of certain individuals. In addition to the detection of a major gene effect, the data suggest that immunity to S. mansoni develops progressively during childhood to reach a maximum around the age of puberty. The implications of these results for the strategy to be used in endemic areas to reduce morbidity and to control parasite transmission are discussed.

Eosinophil-mediated killing of schistosomula of Schistosoma mansoni: oxidative requirement for enhancement by eosinophil colony stimulating factor (CSF-alpha) and supernatants with eosinophil cytotoxicity enhancing activity (E-CEA)

Factors which enhance eosinophil-mediated killing of antibody-coated schistosomula of Schistosoma mansoni include semipurified eosinophil colony stimulating factor (CSF-alpha) and eosinophil cytotoxicity enhancing activity (E-CEA) present in supernatants from cultured mononuclear cells. We have examined the mechanism of enhancement. Both actions require oxygen in order to enhance killing and do not enhance killing under anaerobic conditions (P less than or equal to 0.005). E-CEA had no detectable effect upon oxidative metabolism. In contrast to CSF-alpha which, in our previous studies, increased superoxide anion productions and quantitative leukocyte iodination, E-CEA had no detectable effect upon oxidative metabolism. In order to test whether active oxygen products might mediate enhancement of killing, the effects of the addition of superoxide dismutase and catalase were tested. Neither enzyme showed inhibition of CSF-alpha or E-CEA enhancement of eosinophil-mediated killing. The effects of CSF-alpha and E-CEA were not additive. These studies suggest that both CSF-alpha and E-CEA exert enhancement of killing by means of an as yet unidentified oxygen requiring process.

Suppressive effects of anti-mu serum on the development of collagen arthritis in rats

Sprague-Dawley rats were maintained in environmentally isolated conditions and some of them were injected beginning at birth with rabbit anti-mu serum to suppress B-cell maturation. All rats were subsequently immunized with chick type II collagen. Ten (28%) of 36 rats injected with anti-mu antiserum failed to develop serum hemagglutinating antibodies to collagen, and there was a significant (P less than 0.0003) reduction in the IgG-specific antibody titer to collagen in these 10 rats compared to the other 26 rats in this group. Only 1 (10%) of the antibody-suppressed rats developed arthritis compared to 20 (77%) of the 26 other rats in the anti-mu-treated group (P less than 0.001). Twenty-two (61%) of 36 immunized rats administered rabbit anti-ovalbumin serum and 14 (88%) of 16 immunized rats kept in the axenic conditions developed arthritis. Delayed-type hypersensitivity to collagen did not differ significantly between the groups. These data provide indirect evidence that antibodies play a role in the inception of collagen arthritis.

Eosinophil activation by colony-stimulating factor in man: metabolic effects and analysis by flow cytometry

Substantial increases in the killing capacity of human eosinophils after in vitro incubation with human placental conditioned medium (HPCM), a standard source of colony-stimulating factor (CSF), have recently been described. In this article, the interaction between HPCM and purified human eosinophils is analyzed by flow cytometry and by effects on iodination, superoxide production, and protein synthesis. HPCM increased the intensity of natural eosinophil autofluorescence (aFlu) (460 nm) after the absorption of ultraviolet light (360 nm) in a manner that was both time and dose dependent. Measured in arbitrary units, eosinophil aFlu was 72 +/- 7.3 (arithmetic mean +/- SEM) and 121 +/- 3.2 after 18-hr incubations in the absence or presence of HPCM, respectively. The activity in HPCM responsible for these changes cochromatographed on Ultrogel AcA44 columns with CSF and with the less hydrophobic variant of CSF (CSF-alpha) on phenyl Sepharose. Mouse spleen, but not mouse lung, conditioned medium was also active on human eosinophils in this assay. Both CSF-alpha and mouse spleen conditioned medium also contain eosinophil colony-stimulating activity (CSA), whereas inactive CSFs with no effect on mature eosinophils, CSF-beta, and mouse lung conditioned medium also lack eosinophil CSA. CSF-alpha stimulated superoxide production of resting eosinophils (from 0.03 +/- 0.03 to 0.47 +/- 0.08 nmole cytochrome-c reduced/10(5) eosinophils) and of eosinophils incubated with preopsonized zymosan (from 0.15 +/- 0.06 to 0.73 +/- 0.07). It also stimulated iodination by resting eosinophils (from 0.76 +/- 0.16 to 2.60 +/- 0.72 nmoles l/10(7) eosinophils/hr) and of eosinophils incubated with preopsonized zymosan (from 7.52 +/- 2.08 to 29.8 +/- 1.32). In contrast, CSF-beta was inactive in these assays. CSF-alpha also stimulated, between 2- and 15-fold, the new protein synthesis of eosinophils. Thus, substances that stimulate the differentiation of progenitor cells into eosinophils also interact with peripheral mature eosinophils, and the activation of postmitotic cells may be a physiologic role of CSF-like molecules.

Maturation in vivo of Schistosoma mansoni schistosomula after culture in vitro with granulocytes and antibody

Seven experiments were carried out to test the relationship between the morphological assay for damage to schistosomula in vitro with toluidine blue and the loss of the ability of damaged organisms to mature in vivo. Schistosomula were prepared by penetration of rat skin and cultured for 12 to 38 h in the presence of various combinations of purified human eosinophils or neutrophils and heat-inactivated human antischistosomular serum. Samples were scored for microscopically detectable damage, and the remaining organisms were injected intravenously into normal mice. These mice were perfused after 5.5 to 7 weeks, and the recovery of adult worms was determined. After culture of schistosomula in medium alone, between 8.4 and 32.7% of injected organisms matured into adult worms. There was no significant difference in the capacity of freshly prepared and cultured schistosomula to mature in vivo. Schistosomula cultured with antibody alone showed no significant damage in vitro, and in only one of seven experiments was there a significant (35%) reduction compared with the medium controls in their capacity to mature in vivo. Schistosomula cultured with neutrophils alone or eosinophils alone showed no significant damage in vitro and no loss of viability in vivo. Schistosomula cultured with neutrophils and antibody showed a 28% reduction in recovery in one experiment but an increase in recovery (12 and 46%) in two other experiments. In contrast, schistosomula cultured with eosinophils and antibody showed evidence of both marked damage in vitro (22 to 93% dead organisms) and loss of viability in vivo (26 to 98% reduction in recovery) in all seven experiments. These findings justify the use of the toluidine blue morphological assay as an estimate of irreversible damage to schistosomula and confirm that human eosinophils and neutrophils differ markedly in their capacity to mediate antibody-dependent damage in vitro.

Immune evasion by Schistosoma mansoni: loss of susceptibility to antibody or complement-dependent eosinophil attack by schistosomula cultured in medium free of macromolecules

Schistosomula of Schistosoma mansoni, recovered either after penetration of cercariae through isolated rat skin or by mechanical transformation of cercariae, become fully resistant after 24-48 h of culture to damage by human blood eosinophils in the presence of human anti-schistosomular sera. Cultured schistosomula are also shown to lose their susceptibility to attack by human eosinophils in the presence of human complement. This resistance is related to the simultaneous reduction of the ability of human anti-schistosomular antibodies and human complement component C3 to bind to the surface of the cultured larvae. The development of insusceptibility to antibody, complement and eosinophil-mediated attack does not require the acquisition by the schistosomula of a protective coat of host or other macromolecules, since it is achieved in chemically defined culture medium free of serum and macromolecules. This supports the hypothesis that schistosomula undergo intrinsic changes which render them insusceptible to immune attack.

Interactions between human eosinophils and schistosomula of Schistosoma mansoni. II. The mechanism of irreversible eosinophil adherence

Previous work (1)(1) has shown that normal human eosinophils show a preferential capacity, in comparison with neutrophils, to bind to antibody- coated schistosomula of Schistosoma mansoni. This effect is attributable to a temperature-dependent function of the eosinophil which renders its binding stable and irreversible by aggregated gamma globulin or Staphylococcus aureus protein A. In contrast, the binding of neutrophils is readily reversible by these agents. It has now been shown that the differences observed between eosinophils and neutrophils is a property of their interaction with living schistosomula. When dead or artificially damaged schistosomula were tested, neutrophils showed a markedly enhanced capacity to adhere, in both the presence and absence of anti-chistosomular serum. Subsequent experiments were designed to test the hypothesis that the strong, stable binding of eosinophils was attributable to degranulation, with release of granule contents which would then serve as ligands to bind the cell to the organism. First, an enhanced adherence both of eosinophils and of neutrophils could be demonstrated in the presence of eosinophil major basic protein (MBP) or of protamine, a high molecular weight cation. Second, the binding of eosinophils induced by concanavalin A (Con A) was found to differ markedly from that induced by antischistosomular serum. Con A-mediated binding of eosinophils was fully reversible by alpha-methyl-mannoside, was not associated with damage to the organism, and did not lead to degranulation of the cell, as estimated by measuring the release of MBP into the culture supernate. However, induction of degranulation of concanavalin A-bound eosinophils, but not of neutrophils, with the calcium ionophore A23187 converted the reaction into one which was no longer reversible by alpha- methylmannoside and in which damage to the organism now did occur. These findings support the hypothesis that the stable binding of eosinophils is associated with degranulation, a process which may contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.

Characterization of the primary IgM response to GAT and GT: conditions required for the detection of IgM antibodies

Primary IgM antibody responses to synthetic linear copolymers of L-glutamic acid, L-tyrosine, and L-alanine were investigated. The appearance of primary IgM anti-GAT antibodies was detected in BALB/c mice by using a solid phase radioimmunoassay (SPRIA) procedure. The finding was verified for GAT in responder mice and GAT-MBSA and GT-MBSA in nonresponder mice in an indirect plaque forming cell (PFC) assay by using a rabbit antiserum directed against the mulambda myeloma protein, MOPC 104E. Facilitated IgM PFC could be inhibited by a purified muK myeloma protein, TEPC 183. Maximal facilitated IgM plaque response was found to precede the IgG response by several days. A direct plaque assay was developed for the detection of IgM anti-GAT plaques using poly-L-lysine (PLL) to couple GAT to sheep erythrocytes (SRBC). GAT-SRBC coupled by the PLL method optimally couple 4 to 5 times less antigen to the indicator cell surface than does the CrCl3-coupling method routinely employed in our laboratory. These findings were extended to a conventional antigen, chicken gamma globulin (CgammaG). We found that a less dense epitope coat on the indicator cell surface favors detection of direct IgM PFC, whereas a more densely coated indicator cell favors the detection of facilitated IgM and IgG PFC responses.

Catabolite modulator factor: physiological properties and in vivo effects

Catabolite modulator factor (CMF) specifically inhibits the expression of operons sensitive to catabolite repression. Systems known to be catabolite independent are not affected by CMF. The rate of metabolism of CMF depends on the extent of catabolite repression: it is slow under conditions of strong repression and high in catabolically derepressed cells. Cyclic AMP does not interfere with the rate of CMF metabolism. It has been found that a certain class of crp mutants are partially resistant to the repressive effect of CMF. Our results provide considerable support for the existence of an additional negative control in the regulation of catabolite repression.

Catabolite repression in Escherichia coli mutants lacking cyclic AMP

The regulation of catabolite repression of beta-galactosidase has been studied in Escherichia coli mutants deleted for the adenyl cyclase gene (cya delta), and thus unable to synthesize cyclic AMP. It has been found that, provided a second mutation occurs either in the crp gene coding for the catabolite gene activator protein (CAP) or in the Lactose region, these mutants exhibit catabolite repression. If the catabolite repression seen in the mutant strains corresponds to the mechanism operating in wild-type cells the results would suggest that the intracellular concentration of cyclic AMP cannot be the unique regulator of catabolite repression.