摘要:

SummaryInbred PVG rats infected with 100 Brugia pahangi infective larvae (L3) divide into rats that develop microfilaraemic infection (Mf+), and those that remain microfilaria negative (Mf‐). All rats had high levels of specific IgG to adult worm and L3 extracts, however, after the onset of microfilaraemia, Mf+ rats had significantly higher levels of IgG to Mf extract. Mf+ rats recognized several antigenic components of each developmental extract that were not responded to by Mf‐ rats. In particular Mf+ rats recognized a triplet of proteins of 61‐67 kD in microfilarial extract from day 74 post infection onwards. This indicated that these proteins were stage specific to Mf and Mf‐ rats had not been exposed to Mf rather than Mf absence being due to a protective antibody response. Analysis of the immunoglobulin isotype usage during infection revealed that each isotype was independent both in its period of induction and the developmental stage to which it responded. The predominant isotypes responding throughout infection were IgG1, IgG2a and IgM. Specific IgG2b and IgG2c were elevated early in infection but after the onset of microfilaraemia antibody of these subclasses was suppressed. The antigenic profiles recognized on immunoblots by IgG1, IgG2a and IgM were very

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00628.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryMonospecific rabbit antisera obtained through experimental immunization with previously purified proteins were used in the ultrastructural localization of two hydatid fluid antigens, in brood capsules and protoscoleces of Echinococcus granulosus of human origin. The antigen‐antibody reaction was revealed by a colloidal gold based method. Reaction was evident in the connective region of the germinal membrane and in the parenchyma of the protoscoleces. Both antigen 5 and antigen B were located in the interstitial material between the parenchymal cells and precisely associated with disorganized areas. The brood capsule wall and the brood capsule contents, the tegument of the protoscoleces, the parenchymal cells, the muscle cells, the calcareous corpuscles and the hooks did not contain antigen 5 or antigen B. Label was not observed in the lumen of the collecting ducts or in the flame cells, although antigen 5 was evident in the periluminal cytoplasm. The origin of the antigens and their release are discusse

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00629.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryType I hypersensitivity reactions in the intestinal tract of sensitized animals may contribute to resistance to reinfection with Fasciola hepatica. Colonic mucosae isolated from previously infected rats were voltage clamped in Ussing chambers. Antigen was prepared as a crude homogenate from adult liver fluke. Assay of serum antibodies against fluke antigen confirmed sensitization. Antigen challenge evoked a rapid onset, transient inward current in sensitized but not in control preparations. Chloride secretion accounted for at least part of the response since the loop diuretic bumetanide reduced the effect of antigen by 61%. Anti‐rat IgE mimicked the response to antigen and desensitized tissues to subsequent antigen challenge. Local synthesis of eicosanoids may mediate the response to antigen since the cyclo‐oxygenase inhibitor piroxicam reduced the response by 76%. In contrast, mepyramine which is a histamine receptor antagonist did not alter the ion transport response evoked by antigen. Tetrodotoxin reduced the response to antigen by 53% implicating intrinsic neurons within the lamina propria as effector cells in the responses of this tissue to antigen. We propose that antigen stimulation of electrogenic chloride movement and consequent fluid secretion in vivo may contribute to a local effector mechanism in prevention of reinfection of previously sensitized ho

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00630.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryIt has been suggested that repeat sequence antigens of Plasmodium falciparum may serve the parasite in immune evasion by modifying the host antibody response and impairing the development of protective immunity. According to this proposal networks of cross‐reactive, repeat sequence malarial antigens have the ability to stimulate a high proportion of all somatically mutated B cells with altered antibody specificity, and thus to hinder the normal process of antibody affinity maturation. To determine the rate at which immunoglobulin mutations produce new reactivities with repeat sequence antigens, hybridoma cell lines specific for the ring‐infected erythrocyte surface antigen (RESA) were examined for the incidence of specificity variants that arose naturally or as a result of treatment with the chemical mutagen ethylmethane sulphonate (EMS). From one of the cell lines variants were readily isolated having reactivity towards a very closely related repeat sequence epitope within the same RESA antigen. However, the other hybridoma/antigen combinations revealed no variants. In general, mutations giving rise to antibodies with altered specificity for related repetitive antigens were not readily induced and only limited support of the hypothesis was obtai

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00631.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryA cysteine protease of Trypanosoma congolense (congopain) elicited IgG1 antibodies in those cattle which exhibited a degree of resistance to disease during experimental infections (Authié et al. 1992, 1993). The aim of the present study was to investigate further the association between anti‐congopain antibodies and resistance to trypanosomiasis, and to provide a lead into the mechanisms responsible for the differential responses to congopain in cattle. Isotype characteristics and kinetics of the antibody response to congopain were studied in three N'Dama (trypanoresistant) and three Boran (susceptible) cattle during primary infection with T. congolense ILNat 3.1. In both groups an IgM response to congopain was elicited, thus demonstrating that congopain is antigenic in both types of cattle. Most of the IgM appeared to be incorporated into immune complexes. IgG was detected as free antibody; IgG1 but not IgG2 was detected. All three N'Dama, but none of the three Boran cattle, mounted a significant IgG response to congopain. Sera from 70 primary‐infected cattle belonging to five breeds of differing susceptibility were tested for their reactivity to congopain. High levels of IgG to congopain were observed in the two trypanotolerant breeds, whereas the three susceptible breeds had lower levels of these antibodies. Crosses between N'Dama and Boran cattle, which exhibit an intermediate susceptibility, had intermediate levels of antibodies. Thus, the results from experimental infections confirmed our initial observations. However, under natural tsetse challenge, repeated infections and trypanocidal treatments in Zebu cattle stimulated as high anti‐congopain antibody levels as in non‐treated trypanotolerant taurin

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00632.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryTrypanosoma brucei slender forms predominate over stumpy forms as the parasite population grows but at the peak of a parasitaemic wave and during remission of infection stumpy forms predominate. To determine whether this change in predominance might be caused by selective killing of slender forms, the fates of slender and stumpy form trypanosomes in two in vitro assays of immune‐mediated killing were compared. Parasite populations in which>90% of cells were of slender morphology were observed to be killed by antibody‐dependent complement‐mediated lysis approximately five times faster than populations in which<15% of cells were slender and most were of intermediate or stumpy morphology. Quantification of the relationship between the proportion of slender forms in the population and the rate of lysis indicated that slender forms were killed approximately 7.3 times faster than other forms. In an opsonization assay, no differences were observed between slender and stumpy forms in the extent to which they attached to macrophages in an antibody‐dependent manner. These results suggest that the change in proportions of slender and stumpy forms at the peak of a parasitaemic wave results from slender forms being more susceptible to complement‐mediated killing as the antibody response

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00633.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryPrevious work from our laboratory demonstrated that the infectivity of the protozoan parasite Leishmania major was enhanced in mice if the infecting inoculum contained salivary gland lysates from the sand fly vector Lutzomyia longipalpis. The present study was designed to address the hypothesis that sand fly salivary gland material may function by inhibiting the host immune response. Results indicated that sand fly saliva inhibited the ability of macrophages to present leishmanial antigens to parasite‐specific T cell

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00634.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe ability of Leishmania mexicana amazonensis to inhibit antigen specific T‐cell proliferation against a non‐parasite polypeptide antigen, poly(LTyr, LGlu)‐poly(DLAla)–poly(LLys), was examined. Infection of mouse peritoneal macrophages by promastigotes blocked the proliferation of the T‐cell line, TPB1. This effect was correlated with the level of parasite infection, and the timing of macrophage infection and antigen addition. Peritoneal macrophages from both BALB/b and C57BL/6 mice showed reduced ability to serve as antigen present

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1993.tb00635.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY