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PubMed2005

Phage displaying peptides mimic schistosoma antigenic epitopes selected by rat natural antibodies and protective immunity induced by their immunization in mice.

AIM: To obtain the short peptides mimic antigenic epitopes selected by rat natural antibodies to schistosomes, and to explore their immunoprotection against schistosomiasis in mice. METHODS: Adults worm antigens (AWA) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked transferred immunoblotting methods with normal SD rat sera (NRS). The killing effects on schistosomula with fresh and heat-inactivated sera from SD rats were observed. Then the purified IgG from sera of SD rats was used to biopan a phage random peptide library and 20 randomly selected positive clones were detected by ELISA and 2 of them were sequenced. Sixty female mice were immunized thrice with positive phage clones (0, 2nd), 4th wk). Each mouse was challenged with 40 cercariae, and all mice were killed 42 d after challenge. The worms and the liver eggs were counted. RESULTS: NRS could specifically react to the molecules of 75,000, 47,000, 34,500 and 23,000 of AWA. Sera from SD rats showed that the mortality rate of schistosomula was 76.2%, and when the sera were heat-inactivated in vitro, the mortality rate was decreased to 41.0% after being cultured for 48 h. The specific phages bound to IgG were enriched about 300-folds after three rounds of biopanning. Twenty clones were detected by ELISA, 19 of them bound to the specific IgG of rat sera. Immunization with these epitopes was carried out in mice. Compared with the control groups, the mixture of two mimic peptides could induce 34.9% (P=0.000) worm reduction and 67.6% (P=0.000) total liver egg reduction in mice. Two different mimic peptides could respectively induce 31.0% (P=0.001), 14.5% (P=0.074) worm reduction and 61.2% (P=0.000), 35.7% (P=0.000) total liver egg reduction. The specific antibody could be induced by immunization of the mimic peptides, and the antibody titer in immunized mice reached more than 1:6,400 as detected by ELISA. CONCLUSION: Specific peptides mimic antigenic molecules can be obtained by biopanning the phage random peptide library and a partially protective immunity against schistosome infection can be stimulated by these phage epitopes in mice.

Animals↗
PubMed1997

[The immune response in rats immunized systemically by the surface protein antigen P1 from streptococcus mutans conjugated with procholeragenoid].

This study was carried out to observe the antibody responses in rats after they were immunized with the surface protein P1 of streptococcus mutans when a special adjuvant was used. Antigen P1 was conjugated covalently with procholeragenoid (PCG), and then Sprague Dawley rats were immunized with P1 or the conjugated antigen P1-PCG subcutaneously or intragastrically. Anti-P1 antibody level was assayed at different time points by ELISA. The results showed that the levels of anti-P1 SIgA antibody in saliva rose when P1-PCG was given subcutaneously or intragastrically; the antibody level following the subcutaneous injection was higher and lasted longer, compared with that following the intragastric administretion. The level of anti-P1 IgG antibody in serum only rose when the rats were immunized subcutaneously. These results implied that mucosal immune response or humoral immune response could be induced subcutaneously when PCG was used as an adjuvant.

Animals↗
PubMed1975

Cells involved in the immune response. XXIX Establishment of optimal conditions for the primary and secondary immune responses by rabbit lymphoid cells in vitro.

Attempts were made to initiate the primary and secondary humoral immune responses to sheep red blood cells (SRBC) in vitro as determined by the hemolytic plaque-forming cell (PFC) response, with cell suspensions prepared from a variety of lymphoid organs of the rabbit- thymus, bone marrow, spleen, appendix, sacculus rotundus, Peyer's patches, popliteal lymph node and circulating leukocytes. A number of different media and gaseous phases were utilized in order to establish the optimal conditions for the immune response in vitro. The induction of a secondary PFC response was consistently obtained with 'memory' spleen cells obtained from rabbits 3-6 months following intravenous immunization with SRBC but not with cells of any of the other lymphoid organs, and this response probably represents the activity of memory cells which reside in the rabbit spleen. A primary response was observed only with 'normal' spleen cells, and the medium which faciliated the response was different from that which facilitated the induction of the secondary response in vitro. It was also observed, using a medium in which normal spleen cells were incapable of generating PFC', that mixed cultures of normal spleen and normal appendix or bone marrow cells could give a marked PFC reponse in vitro. Whether the PFC response to SRBCs obtained with the lymphoid cells of normal, unimmunized rabbits represent a true primary response, a secondary response, or a response of a different nature as a consequence of continuous subthreshold immunization of the rabbit with enteric microorganisms which cross-react with the antigen, remains to be determined. However, out initial successes with cultures consisting of cells of at least two distinct lymphoid organs in cases where the cells of any one of these organs could not respond, suggest that interaction of at least two functionally distinct cells is required and that the repsonse observed in vitro is probably a primary immune response.

Animals↗
PubMed2001

A unique experience with human pre-immune (12 weeks) and hypo-immune (16 weeks) fetal thymus transplant in a vascular subcutaneous axillary fold in patients with advanced cancer: a report of two cases.

BACKGROUND: The successful development of fetal cell/tissue transplantation in adults has resulted in the possibility of eventual therapeutic solutions with a variety of intractable diseases. Umbilical cord whole blood transplantation appears to be safe in the adult system. In severe forms of DiGeorge Syndrome, cultured thymus transplant can help in the reconstitution of the immune condition of the host. Successful fetal tissue transplant in adults has raised the hope of future effective gene transplant and its manipulation prospects to combat many diseases including hemopathies, inborn errors of metabolism, immunodeficiencies and even cancer and AIDS. MATERIALS AND METHOD: Two cases of advanced cancer were treated with fetal (pre-immune 12 weeks and hypo-immune 16 weeks) thymus transplants in subcutaneous vascular axillary folds, which were removed after one month. Thymuses were collected from consenting mothers undergoing hysterotomy and ligation. RESULTS AND ANALYSIS: Patient I was suffering from non-Hodgkins lymphoma (Ann Arbor Stage IV) and was receiving cyclophosphomide, doxorubicin, vincristine and prednisolone after a course of radiotherapy; she developed leucopenia (2.400/cmm), which improved after receiving a 16-week human fetal thymic graft. The leucopenia was eventually over-corrected and the leucocyte count reached 44,000/cmm within a month, which was reversed after the thymus was taken out. Histology of the excised thymic graft showed growth and proliferation without any graft vs. host (GVH) reaction. Patient 2 was suffering from breast duct carcinoma (T4, N2, M0,) with estrogen, progesterone, and epidermal growth factor negative status, and was treated with modified radical mastectomy and axillary clearance followed by chemotherapy with cyclophosphomide, methotrexate and 5-fluorouracil for six cycles. She also received a 12-week-old human fetal thymus at the contra-lateral axilla which was removed after one month. In this case the peripheral leucocyte count did not show appreciable variation as in the first case. However, histology of the excised thymic graft showed growth and proliferation with an appearance of Hassel's corpuscles. CONCLUSION: Pre-immune and hypo-immune human fetal thymic transplant is not rejected in patients suffering from advanced cancer within one month (observation period). Thymic lymphocyte shedding in the correction of leucopenia in the background of non-Hodgkin's lymphoma may have many therapeutic implications.

Adolescent↗
PubMedDate not supplied

Induction of humoral immune response and protective immunity in chickens against Salmonella enteritidis after a single dose of killed bacterium-loaded microspheres.

Formalin-inactivated Salmonella enteritidis phage type 4 strain 119/95 (SE) was encapsulated in biodegradable poly (DL-lactide co-glycolic acid) PLGA; (65:35) microspheres by a modified water-in-oil-in-water (w/o/w) double-emulsion solvent extraction/evaporation technique. These SE-loaded microspheres (SE-MS) were porous and spherical in shape with diameters of 0.4-10 microm and 20-80 microm in two preparations. SE-MS were subsequently used to vaccinate specific-pathogen-free chickens in a single dose in order to investigate the potency of a single-dose vaccination in inducing immune responses and protective immunity. In Experiment 1, 4-wk-old chickens that were vaccinated intramuscularly with 20-80-microm SE-MS generated long lasting (over 6 mo) and persistently high serum anti-SE immunoglobulin (Ig)G antibody response. In Experiment 2, 2-wk-old chickens were vaccinated orally with 0.4-10-microm or intramuscularly with 20-80-microm SE-MS and challenged with 10(9) colony-forming units of homologous SE strain at 6 wk postvaccination. When challenged intramuscularly, one each of the orally vaccinated (n = 10) and the intramuscularly vaccinated birds (n = 10) showed clinical signs and death, whereas all of the nonvaccinated control birds (n = 12) were sick and 11 of them were killed. When challenge was via oral route, 26.1% of cloacal swabs and 24.0% of organs (liver, spleen, and cecum) collected from orally vaccinated birds (n = 35) were positive for SE, comparable to 27.9% of feces and 18.7% of organs from the intramuscularly vaccinated birds (n = 35). These figures were significantly lower than those for nonvaccinated birds (n = 30) from which 59.3% of feces and 44.0% of organs tested SE positive (P < 0.05). The humoral immune response was also determined after vaccination with a single dose. The intramuscular vaccination elicited higher serum IgG response than oral administration, but the latter elicited a significant intestinal mucosal IgA antibody response. This is the first evidence that chickens vaccinated with killed SE-loaded PLGA microspheres, intramuscularly and orally in a single dose, developed systematic and local immune responses, thereby conferring protective immunity.

Administration, Oral↗
PubMed1999

[Schistosoma japonicum: protective immunity induced in mice immunized with SjGST-Sj32].

Schistosoma japonicum glutathione-s-transferase (SjGST), Schistosoma japonicum 32,000 protein (Sj32) and SjGST - Sj32 were expressed and purified to study on protective immunity against Schistosoma japonicum. The result showed that compared with the adjuvant control group, the worm burden was decreased significantly in mice immunized with recombinant SjGST - Sj32, Sj32 and Sj32 + SjGST (P < 0.05). At the same time, the liver egg per gram(EPG) was decreased in mice immunized with SjGST - Sj32, Sj32, Sj32 + SjGST and SjGST. It is concluded that Sj32 significantly induces both protective immunity and anti-fecundity immunity, but SjGST only has an anti-fecundity effect.

Animals↗
PubMed2003

Plasmid-based vaccines encoding rat neu and immune stimulatory molecules can elicit rat neu-specific immunity.

DNA vaccines are ideally suited for immunizing against tumor antigens because constructs can be formulated that not only encode the tumor antigen but also encode molecules chosen to improve the ability to elicit an antitumor response. Ligands expressed on antigen-presenting cells associated with stimulating a robust T-cell response are excellent candidates for inclusion in a DNA vaccine. Mice transgenic for the HER-2/neu homologue, rat neu, were immunized with full-length rat neu cDNA given alone or in combination with plasmids encoding costimulatory molecules CD80 or CD86 and the ligand for CD137 (CD137L). Intradermal injection of the plasmid constructs resulted in both plasmid transcript and antigen protein expression being detected in lymph nodes draining the injection site. Immunization with plasmids encoding the neu antigen along with plasmids encoding CD137L and either CD80 or CD86 resulted in the generation of neu-specific antibodies that induced phopshorylation of the neu tyrosine kinase and inhibited the growth of cultured tumor cells overexpressing neu. Survival of animals was significantly prolonged after immunization with vaccines encoding neu together with the costimulatory molecules. Although tumors eventually occurred in the vaccinated animals, they were markedly infiltrated with CD4+ T cells. DNA vaccines encoding neu, when given in combination with both CD137L and either CD80 or CD86, can induce cellular and humoral immunity and result in an antitumor effect.

Animals↗
PubMed2003

[C3d molecular adjuvant increases the immunity of human chorionic gonadotropin beta DNA contraceptive vaccination and changes its immune response from Th1 to Th2].

OBJECTIVE: To testify the effect of C3d molecular adjuvant on the immunogenicity of human chorionic gonadotropin beta (hCG beta) DNA vaccination as well as the mode of immune response. METHODS: BALB/c mice aged 6 weeks were immunized intramuscularly two times at an interval of 3 weeks with by the plasmid pcDNA3 (A1-3 groups), pcDNA3-hCG beta (B-3 groups), pcDNA3-hCG beta-C3d3 (C1-3 groups), or pCMV4-hCG beta-C3d3 (D1-3 groups), at dosage of 5 pmol, 10 pmol, and 20 pmol, respectively. Three weeks after the second vaccination the animals were killed, specimens of their peripheral blood were extracted to determine the anti-hCG beta antibody titer by indirect ELISA. Their spleen cells were harvested and stimulated in vitro by hCG antigen for 24 hours. The Th1/Th2 cytokines in the culture supernatant were determined by ELISA. RESULTS: At the dosage of 20 pmol, C3d molecular adjuvant significantly enhanced the anti-hCG beta antibody titer. The utmost anti-hCG beta antibody titer of C3 group was 1:450, 9 times higher than that of B3 group, and the utmost anti-hCG beta antibody titer of D3 group was 1:12 150, 243 times higher than that of B3 group. Stimulated in vitro by 5,000 IU hCG beta antigen, the splenic cells of the C3 and D3 immunization group produced significantly lower IL-2, INF-gamma and TNF-alpha than those of the B3 immunization group (P < 0.01 or P < 0.05). The IL-4 level of the C3 group was higher than that of the B3 group while the IL-10 level of the D3 group was significantly higher than that of the B3 group (P < 0.01). CONCLUSIONS: The C3d molecular adjuvant increases significantly the hCG beta immunogenicity of hCG beta DNA vaccination; meanwhile decreases the secretion of Th1 cytokines (IL-2, INF-gamma, and TNF-alpha), and increases the expression of Th2 cytokines (IL-4 and IL-10) in response to hCG antigen. So C3d changes the anti-hCG immune response from Th1 type to Th2 type.

Adjuvants, Immunologic↗
PubMed2005

CD8+ T-cell-dependent immunity following xenogeneic DNA immunization against CD20 in a tumor challenge model of B-cell lymphoma.

The CD20 B-cell differentiation antigen is an attractive target for immunotherapy of B-cell lymphomas. In an experimental lymphoma model, BALB/c mice were immunized with mouse or human CD20 cDNA (mCD20 and hCD20, respectively) or their extracellular domains (minigenes). IFNgamma secretion by CD8+ T cells against CD20 was detected in mice vaccinated with hCD20 or human minigene, indicating that hCD20-primed CD8+ T cells recognize syngeneic CD20. Systemic challenge with syngeneic A20 cells, an aggressive lymphoma, resulted in long-term survival in a subset of immunized mice. Overall long-term survival was 14% in groups vaccinated with the human minigene versus 4% in control groups (P < 0.001). CD8+ T-cell depletion during the effector phase completely abrogated this effect. Antibodies against a recombinant mouse CD20 protein produced in insect cells were detected in mice immunized with hCD20 DNA and human and mouse minigene, but not in mice receiving mCD20 DNA. These results show that active immunization with xenogeneic DNA vaccines can induce CD8+ T cell-dependent immunity against CD20.

Animals↗
PubMed1992

Immunity to and immunization against measles, rubella and mumps in patients after autologous bone marrow transplantation.

Humoral immunity to measles, rubella and mumps was studied in 63, 36 and 16 patients 1, 2 and 3 years, respectively after autologous bone marrow transplantation (ABMT). Serologic examination was performed using antibody-ELISA. One year after ABMT, 7/57 patients (12%) who were seropositive to measles before ABMT, became seronegative, 8/44 (18%) to rubella and 3/51 (6%) to mumps. Among patients who were retested at 2 and 3 years, three more patients became seronegative to measles, one to rubella, and three to mumps. Nine of 12 children who had previously been immunized against measles were seropositive before ABMT, 3/7 to rubella and 5/7 to mumps, respectively. After ABMT, 5/9 became seronegative to measles, none to rubella and 2/5 to mumps. Six seronegative children were immunized with a live trivalent attenuated measles, mumps, and rubella vaccine 1 to 2 years after ABMT. Two children seroconverted to measles, six to rubella, and four to mumps. No side effects were observed. Most adult patients who have had the diseases of measles, rubella, or mumps naturally remain seropositive, while children who have been immunized commonly lose their immunity after ABMT.

Adolescent↗
PubMed1991

The effect of total or partial T lymphocyte depletion on susceptibility to influenza virus infection and development of antiviral immunity in lethally irradiated mice reconstituted with immune syngeneic bone marrow grafts.

In a previous study, we showed that lethally irradiated mice reconstituted with bone marrow (BM) enriched with spleen cells obtained from A/PR8/34 influenza virus-immune donors had an improved survival rate compared to the survival seen in recipients of naive BM, immune BM or T cell-depleted BM obtained from immune mice. Our purpose was to determine which cell population was responsible for this effect. We therefore compared the resistance to influenza virus of lethally irradiated BALB/c mice reconstituted with BM from immune donors enriched with 20% spleen cells following either incubation with anti-Thy-1, anti-Lyt-2 or anti-L3T4 monoclonal antibodies prior to transplantation, thereby leading to in vivo depletion of antibody-treated lymphocyte subsets. Mice were infected with influenza virus 1 day after BM transplantation. Equal survival rates were observed in recipients of unmanipulated BM and spleen cells obtained from immune donors and recipients of similar inocula treated with monoclonal anti-helper (L3T4) or anti-cytotoxic/suppressor (Lyt-2) antibodies prior to inoculation. The survival rate of all these groups was increased in comparison with mice receiving anti-Thy-1 treated BM and spleen cells, suggesting that both L3T4 and Lyt-2 T cell subsets play a role in protection against virus infections.

Animals↗
PubMed1991

The initial immune response to HIV and immune system activation determine the outcome of HIV disease.

A study was conducted to assess the relative contribution of the HIV-1-specific immune response and -nonspecific immune activation to HIV disease progression. The titer of antibody to the p24 core protein and the concentration of serum neopterin were measured in 238 HIV-1-seropositive subjects in a prospective cohort study of homosexual men. Antibody titers were extremely variable among cohort participants but relatively stable over time, suggesting inherent differences in the initial immune response capacity. Neopterin concentrations were also variable at cohort entry but generally increased over time. These two markers, measured at cohort entry, had powerful and independent predictive value for the development of AIDS up to 54 months before diagnosis. Subjects with low antibody titers and high levels of neopterin, had the highest incidence of AIDS (60% over 54 months). Patients with low antibody or high neopterin alone had an intermediate risk (34% incidence) and less than 10% of those with high antibody and low neopterin developed AIDS. We propose that the initial immune response to HIV and virus-mediated immune system activation are independent and innately variable components of an individual's response to HIV infection that interact to determine the clinical outcome.

Acquired Immunodeficiency Syndrome↗
PubMed2006

[Immune adjuvant effect of TB.HSP70 to its accompanying cytotoxic T lymphocytes epitope elicits HBV specific immune response].

OBJECTIVE: To investigate whether Mycobacterium tuberculosis heat shock protein 70 (TB.HSP70) can be used as an adjuvant carrier to stimulate immune response to an accompanying cytotoxic T lymphocytes (CTL) epitope peptide from hepatitis B virus (HBV) core antigen. METHODS: In vitro, peripheral blood mononuclear cells (PBMCs) from chronic hepatitis B volunteers were stimulated with TB.HSP70-CTL fusion protein and TB.HSP70/CTL complex, and then HBV specific CTL activity was assessed. In vivo, the CD4+ T, CD8+ T and natural killer cells (NKs) in the peripheral blood and in spleens of the immunized mice were measured by flow cytometry and the protective HBV specific immune responses of the mice were also evaluated. RESULTS: The results revealed that both of them could induce HBV specific CTL response in human PBMCs and in the immunized mice. In the mice they activated CD4+ T, CD8+ T and NKs. Furthermore, the immunocompetence of the TB.HSP70-CTL fusion protein was stronger than that of TB.HSP70/CTL complex. The HBV specific killing rate was 28.9%, the CD8+ T cell population was 43.9% and the NKs was 13.6% in splenocytes of immunized mice with TB.HSP70-CTL fusion protein. The CTL peptide alone was capable of generating weak CTL lysis. The TB.HSP70 showed almost no target cell killing. CONCLUSION: The results demonstrate that TB.HSP70 may be used as a new adjuvant carrier to improve the immunogenicity of short CTL epitope and produce effective CTL response.

Adjuvants, Immunologic↗
PubMed1991

Allotype-linked immune response genes: roles in network control of the immune system.

Studies on allotype-linked immune response genes and related genes are overviewed with particular attention to our current results in unique models. Significance of actions of various immune response genes in relation to allelic polymorphism of molecules in the immune system is discussed. The molecules involve immunoglobulins, T cell receptors, major histocompatibility complex and a number of cell interaction molecules, many of which belong to the immunoglobulin superfamily. Differential roles of V-linked and C-linked immune response genes for network control of the immune system, preparing the V structure repertoire, controlling antigen presentation and modulating the effector mechanism, are suggested.

Animals↗
PubMed1991

Guatemalan human onchocerciasis. II. Evidence for IgG3 involvement in acquired immunity to Onchocerca volvulus and identification of possible immune-associated antigens.

Ag-specific isotypic differences in immune response to Onchocerca volvulus Ag were assessed for 778 long term residents of endemic Guatemalan areas by quantitative ELISA with 5-min incubation steps and immunoblot. The study population was separated into five groups based on clinical status: N+F+, N+F-, N-F+, N-F-H+, and N-F-H-, where N = O. volvulus adults (nodule), F = microfiladermia, and H = history of O. volvulus infection. A subset of 44 individuals with high exposure to onchocerciasis from the N-F-H- group were critically evaluated and designated as "putatively immune." IgG1 reactivity to O. volvulus Ag was elevated in the majority of infected persons, but not in putatively immune individuals. Specific IgG3 levels, however, were equally elevated in all groups. The majority of N+F- persons also had elevated IgG1 levels, but they were lower than those found in F+ persons. IgG3 reactivities to a group of antigens at 20 kDa (GP20) were seen in many uninfected persons and some N+F- persons. In contrast, most F+ persons, react to this Ag with IgG1 and not IgG3. A mangabey inoculated with the infectious larval stage of O. volvulus (L3), but showed no signs of infection, began to recognize GP20 at 2 wk postinoculation. Early recognition of GP20 was possibly elicited by the larval stage. Purified nodule Ag from N+F+ individuals contained GP20, however, identical nodule Ag prepared from N+F- individuals did not. These data suggest that GP20 Ag may be common to both uterine microfilaria and the infectious larval stages. The fact that GP20 is predominantly recognized by IgG3 in putatively immune persons and some N+F- persons suggests that this increased IgG3 activity may be important in acquired immunity to onchocerciasis.

Adolescent↗
PubMed1988

Glomerular immune deposits in experimental IgA nephropathy. A continuum of circulating and in situ formed immune complexes.

Studies were undertaken to elucidate the primary pathogenetic mechanisms responsible for immunoglobulin (Ig) A immune complexes formation and glomerular deposition in vivo. Monomeric (mIgA) and polymeric IgA (pIgA) anti-dinitrophenyl (DNP) were purified from MOPC 315 myeloma. A DNP-conjugated Ficoll was used as an antigen. For simulation of natural conditions of in vivo immune complex formation, 131I-DNP-Ficoll and 125I-IgA were administered through the intravenous and intraperitoneal routes, respectively. The kinetics half-life (t1/2) of the antigen (2.9 hours) and either the pIgA (7.2 hours) or mIgA (6.3 hours) in the experimental groups was not significantly different from the control. Glomerular IgA immune deposits were detectable only in mice that received pIgA and DNP-Ficoll. Plasma samples analyzed by gradient polyacrylamide gel electrophoresis revealed formation of large- and intermediate-sized pIgA complexes in circulation prior to glomerular deposition. Although mIgA failed to interact with such complexes in the circulation, it did bind to the pIgA immune deposits in the glomerulus. These results indicate that glomerular IgA immune deposits evolve from the localization of preformed circulating pIgA complexes that eventuates an in situ mIgA-mediated complex formation.

Animals↗
PubMed1976

Autogenous immunity to endogenous RNA tumor virus: humoral immune response to virus envelope antigens.

Autogenous immune sera from several strains of mice have been examined for type-, group-, or interspecies-specific reactivities against leukemia virus envelope antigens and virus-induced cell surface proteins. The natural antibody of these test sera react with gp69/71, gp43, and p15 structural components on murine leukemia viruses including AKR, Friend, Rauscher, Moloney, and xenotropic BALB:virus-2. Furthermore, comparable radioimmune titration curves are obtained when these viruses are used in radioimmune precipitation assays. Competition experiments, however, suggest that natural immune sera are predominantly type specific and only weakly cross-react with the Rauscher or Friend virus. Natural immune sera react with the virion envelope but not with the virus-induced cell surface antigen. With respect to the biological activity of autogenous immune sera, there appears to be an inconsistency between the spectrum of virus-precipitating antibody and virus-neutralizing antibody. Although normal mouse serum readily neutralizes xenotropic viruses (BALB:virus-2), only weak neutralization of the ecotropic viruses can be achieved in vitro. Although there is a lack of direct evidence to indicate that autogenous immunity to murine leukemia virus is involved in the control of virus-mediated neoplasia, several empirical correlations point in this direction.

Animals↗
PubMed1981

Immune response gene control of determinant selection. III. Polypeptide fragments of insulin are differentially recognized by T but not by B cells in insulin immune guinea pigs.

Synthetic polypeptides corresponding to restricted regions of the B chain of insulin were used to evaluate immune response gene control of guinea pigs immune to native insulin. The amino acids necessary for recall of immune memory were assessed at the level of the T cell by use of peptides 8 to 16 amino acids in length, representative of the amino terminus of the insulin B chain to induce antigen-specific proliferation and help for antibody formation. A single histidine residue in the 10th position of the B chain is critical for T cell activation. In addition, immune response genes operating in the macrophage discern the presence or absence of this residue and activate the appropriate T cell clones. Although receptor V region sharing may exist for T and B cells immune to globular proteins, it cannot be demonstrated by antigen specificity, since T proliferation and generation of T helper cells in response to intact insulin can be elicited by synthetic fragments that do not correspondingly induce antibodies that recognize the native molecule.

Amino Acid Sequence↗