摘要:

SummaryThe majority of protein antigens of the malaria parasitePlasmodium falciparumcontain short sequences that are extensively repeated in tandem arrays. Some antigens contain a single block of repeats whereas in other antigens there may be two or more blocks of related repeats. The repetitive sequences in an individual antigen may be highly conserved but more usually there is some degeneracy which occasionally is extensive. The repetitive sequences encode immunodominant epitopes to which much of the antibody response in malaria is directed. Recently, we have found that there are extensive cross‐reactions amongst the epitopes encoded by related repetitive sequences. These cross‐reactions may involve different blocks of repeats in the one antigen or repetitive sequences in different antigens. It is proposed that these cross‐reactions interfere with the normal maturation of a high affinity antibody response in malaria by causing an abnormally high proportion of somatically‐mutated B cells to be preserved during clonal ex

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00867.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryThe host response toPlasmodiaincludes the production of enlarged populations of peripheral blood monocytes and tissue macrophages in the spleen and the liver. Since the hyperplasia of the mononuclear phagocyte system is believed to arise as a consequence of an enhanced blood monocyte influx, we tested monocyte chemotactic responsiveness in 19 patients with acute primary attack malaria. In addition, the neutrophil chemotaxis was measured in 12 patients. Before the initiation of antimalarial treatment a significant depression of monocyte chemotaxis was observed in approximately half of the patients when compared with healthy control subjects. The depression was found inPlasmodium falciparummalaria as well as inP. vivaxorP. ovalemalaria patients. The defective responsiveness was not receptor specific, since the responses towards casein and zymosan activated serum proved to be equally suppressed. The monocyte chemotaxis was followed in 14 of the patients, during treatment and after complete recovery. After 3 days of treatment the response had improved in most of the patients, and after 7 days all patients had a normal monocyte chemotaxis, which remained normal after one month. No significant differences betweenP. falciparumandP. vivax/ovalemalaria was observed with respect to blood monocyte chemotactic responsiveness. Neutrophil chemotaxis in patients withP. falciparuminfections was similarly suppressed before treatment (54% of controls), was still defective after 3 days of treatment, and nearly normalized after 7 days (87% of controls). Furthermore, monocyte phagocytic and candidacidal activities were assessed in the same patients on admission and during the follow‐up. In contrast to chemotaxis, these functions were normal in all of the patients whenever measured. In conclusion, not all cell functions were altered in concert, and the previously unreported suppression of chemotactic migration might reflect a change in blood leucocyte subpopulations, deactivationin vivoor a direct suppressive effect of Plasmodia induced product

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00868.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryThis paper reports the results ofin vitroexperiments which attempt to elucidate the mechanisms whereby Gambian children control acute infections ofPlasmodium falciparum.It was shown initially that mononuclear cells from children with acute malaria, in the presence of specific antibody, caused a marked reduction inin vitroparasite growth. IgM antibodies appeared to be considerably more effective than IgG. T or B lymphocytes were ineffective in the system; adherent cells alone had some effect, but much less than the unfractionated cell population. Adherent cells were however fully effective after exposure to supernatants from T cells activated either non‐specifically by phytohaemaggluti‐nin (PHA), or specifically byP. falciparumantigens. Depression of parasite growth was also observed, independent of anti‐malarial antibody. This was achieved when adherent cells from healthy Europeans, as well as those from infected children, were exposed to the supernatants from previously stimulated T cells before adding to the culture. Furthermore, intra‐erythrocytic parasite death occurred after a short exposure to the supernatants of ‘activated’ adherent cells from both infected children an

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00869.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryImmunoprecipitations ofin vitrotranslation products of mRNA from adultSchistosoma mansoniworms with sera from chronically infected mice of 12 inbred strains reveal a strain‐dependent heterogeneity in the antibody responses to schistosome antigens. Of the strains tested the response to the 86K antigen was restricted to mice of haplotypes H‐2dH‐2k, and H‐2kwhile the 14K antigen was only recognized by H‐2kmice. Responses to other antigens revealed the influence of non‐H‐2 genes on the antibody response although no clear correlation was apparent between the antigens recognized and the non‐H‐2 genes of the strains. Both dominant and recessive responses towards individual antigens were seen in F| animals. Some of these results support the cross tolerance model

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00870.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryA simple method for producing monospecific rabbit antisera, applied originally to the constituents of human serum (Goudieet al.1966), has been adapted for use withSchistosoma mansoniegg antigens. Replicate isolated immunoprecipitin arcs resulting from the immunoelectrophoretic reaction between an egg antigen and a polyspecifk antiserum were excised, washed extensively to remove non‐precipitated contaminants, homogenized, and emulsified with complete Freund's adjuvant. Rabbits were given weekly subcutaneous injections of the emulsion in multiple sites, and a monospecific precipitating antibody against the respective immunizing antigen generally resulted within 6 weeks of the commencment of immunization. Antisera raised in this manner againstS. mansoniegg antigens tui, oti andKshave been used to characterize the antigen with respect to their stage‐ and species‐specificity. After immunoabsorp‐tion to remove background activity, the sera could be used to detect unequivocally the respective antigens in crude egg homogenate that had been subjected to SDS‐PAGE and electrotransfer to nitrocellul

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummarySurface antigens of muscle larvae ofTrichinella spiraliswere stripped from the cuticle of live worms by the cationic detergent cetyltrimethylammonium bromide (CTAB). Such antigen preparations were shown to contain surface antigens of approximate molecular weights 100000, 90000, 69000, 55000, 46000 and 35000. Immunoprecipitation experiments confirmed that the surface of muscle larvae share antigenic epitopes with antigens contained within and secreted by the stichosome. CTAB antigen preparations were shown to be protective in NIH mice against a challenge infection as assessed by reduction in intestinal worm burden, worm fecundity, worm length and muscle larvae burden. The role of surface antigens in protective immunity toT. spiralisis discussed.

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummarySurface properties of developing stages ofTrichuris muriswere investigated by analysis of binding affinities for specific anti‐parasite antibodies present in a range of infection sera;in vitroeosinophil adherence studies; and binding of the fluorescent‐labelled lectins, Con A, WGA, PNA and RCA. In general, larvae of any one particular stage did not bind anti‐parasite antibodies present in serum collected at an earlier stage of the infection, thus indicating a considerable degree of antigenic stage‐specificity. Forty day and older parasites displayed similar binding properties and it is suggested that no major changes in surface antigenicity occur after the final moult at day 25–30 after infection. Surface properties were also examined by means of complement and antibody‐mediated eosinophil adherence assays. Attachment of eosinophils was maximal with day 5 larvae, although even at this stage not all of the parasite surface was covered with attached cells. Despite adherence, eosinophils were unable to effect parasite killing, even after 48 h of incubation. These studies showed that eosinophil adherence‐promoting antibodies were present in immune sera; that the larval parasite surface was able to activate complement by the alternate pathway with subsequent generation of C3b molecules, and that the parasite was able to withstand eosinophil adherence and secretion by an as yet unidentified evasive stratagm. Studies with fluorescent‐labelled lectins showed that all larval stages (days 5–25 after infection) were positive for Con A binding. Early larval stages (days 5–10 after infection) also bound PNA and WGA. Interestingly, recently moulted individuals rarely exhibited fluorescence, but cast cuticles

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryA monoclonal antibody (NIM‐M7) has been prepared which reacts with a major surface antigen of adult males and females ofTrichinella spiralis.This specificity is only demonstrable when the antigen is liberated by detergent solubilization of surface‐labelled worms. When reacted with living adults, on the other hand, NIM‐M7 reacts well with only the eversible cloaca, or copulatory bell, of the male, binding weakly, if at all, to other surface areas of male or female worms. A similar staining pattern is also given by Concanavalin A. The differential staining given by NIM‐M7 must indicate a molecular difference between the organization of the same surface antigen on the cuticular surface of the copulatory bell and other areas of the worm surface. This example of regional specialization demonstrates that the nematode cuticle is not necessarily chemically

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00874.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummaryAn animal model for the study of transient lymphadenopathy‐splenomegaly during toxoplasmosis is presented. Injection of CBA/J mice with the low virulent, cyst‐forming strain ofToxoplasma gondii(Pe strain) induces a three to four fold increase in weight and cellularity of spleen and lymph nodes with peak changes at 30–50 days after infection. The spleen displays marked haemopoiesis, a 30 fold increase in mononuclear phagocytes, and a two fold increase in Lyt2+lymphocytes. Lymph nodes show a five fold increase in mononuclear phagocytes and a four and a half fold increase in Lyt2+T cells. The increase in mononuclear phagocytes significantly alters T cell/macrophage ratios and this is associated with decreases inin vitrocell proliferation to mitogen and toxoplasma antigen. The relationship between alterations in cell balance of mononuclear phagocytes and T cell subsets and the expression of transient immune dysfunction can now be examined by modulating changes in these cell

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00875.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SummarySeveral physicochemical characteristics of the repeated epitope of the major surface protein (P30) ofToxoplasma gondiiwere investigated with an anti‐P30 mAb by two different methods: (a) a one‐site/inhibition assay that detects molecules containing single or multiple epitopes and (b) a two‐site/one antibody radiometric assay that is only effective with antigenic molecules containing two or more identical epitopes. Using both techniques, the repeated epitope within purified P30 was stable after 1 h at 63°C, but labile at 100°C. It was also resistant to successive freezing and thawing, and not affected after one year at – 70°C. Lyophilization and acidic or basic treatment had no effect. This epitope was also resistant to 20% trichloroacetic acid precipitation (activity recovered in the pellet) and to precipitation with cold acetone.To investigate the immunodominance of this repeated epitope during the humoral immune response againstT. gondii, competition binding assays between anti‐P30 mAb and polyclonal antibodies, from rabbits immunized with either purified P30 or totalToxoplasmaextract and from patients with toxoplasmosis, have been used. We found that the mAb inhibited 50–95% of the binding of the IgG antibodies from both rabbits to purified P30. In addition, the binding of both human IgG and IgM antibodies to P30 was significantly inhibited by the mAb. It appears, therefore, that a single region of P30 contains most of the immuno

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1986.tb00876.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY