National outbreak of Salmonella senftenberg associated with infant food

Eight cases of Salmonella senftenberg infection in infants were identified in the first half of 1995 in England, five were indistinguishable S. senftenberg strains. A case-control study showed an association between illness and consumption of one brand of baby cereal (P = 0.03). The cereal manufacturer reported isolating S. senftenberg in June 1994 from an undistributed cereal batch. Outbreak strains and the cereal strain were all plasmid-free in contrast to other human isolates of S. senftenberg in the same period. Changes in the production process were implemented to prevent further contamination. Surveillance centres should strengthen the detection and investigation of outbreaks of gastrointestinal infection in susceptible groups, especially young children. In this outbreak, the study of only five cases led to identification of the vehicle of infection. Even when few cases are reported, epidemiological investigation in conjunction with molecular typing may lead to public health action which prevents continuing or future outbreaks.

Restricted TCR V alpha repertoire in the T cell response to a tolerogenic determinant of type II collagen

Tolerization of B10.RIII mice (H-2r) with i.v.-injected type II collagen (CII) renders the animals resistant to induction of collagen-induced arthritis (CIA). The B10.RIII mouse is of particular interest, in that the T cell determinants that induce tolerance are different from those that induce arthritis. To characterize T cells that react with the tolerogenic determinant and play a role in regulation of arthritis, we have developed a panel of T cell hybridomas reactive with the tolerogenic T cell epitope, CII 607-621. None of the hybrids cross-reacted with either the arthritogenic CII 445-453 or murine CII. As determined by PCR and immunofluorescence, the T cell response to the tolerogenic determinant was oligoclonal, with evident preferential usage of V alpha. Through the analysis of a large panel of T cell hybridomas, preferential usage of V alpha2, J alpha44, J beta2.7, and D beta2.1 was observed. Characterization of T cells reactive with the immunodominant determinant, CII 607-621, responsible for the induction of tolerance should prove important in developing novel therapeutic approaches for the treatment of autoimmune diseases.

Restricted TCR V alpha repertoire in the T cell response to a tolerogenic determinant of type II collagen

Tolerization of B10.RIII mice (H-2r) with i.v.-injected type II collagen (CII) renders the animals resistant to induction of collagen-induced arthritis (CIA). The B10.RIII mouse is of particular interest, in that the T cell determinants that induce tolerance are different from those that induce arthritis. To characterize T cells that react with the tolerogenic determinant and play a role in regulation of arthritis, we have developed a panel of T cell hybridomas reactive with the tolerogenic T cell epitope, CII 607-621. None of the hybrids cross-reacted with either the arthritogenic CII 445-453 or murine CII. As determined by PCR and immunofluorescence, the T cell response to the tolerogenic determinant was oligoclonal, with evident preferential usage of V alpha. Through the analysis of a large panel of T cell hybridomas, preferential usage of V alpha2, J alpha44, J beta2.7, and D beta2.1 was observed. Characterization of T cells reactive with the immunodominant determinant, CII 607-621, responsible for the induction of tolerance should prove important in developing novel therapeutic approaches for the treatment of autoimmune diseases.

Community immunization programme in response to an outbreak of invasive Neisseria meningitidis serogroup C infection in the Trent region of England 1995-1996

Between 8 December 1995 and 16 January 1996 seven laboratory confirmed cases of septicaemia owing to infection with Neisseria meningitidis serogroup C strains and one highly probable case of meningococcal septicaemia occurred in three electoral wards in south Rotherham and the Retford area of north Nottinghamshire. All cases occurred among children aged 1-17 years. One patient died. The public health response to this outbreak was the largest community prophylactic antibiotic and immunization programme against meningococcal infection, to date, in the United Kingdom. The target group for each Health Authority was 8900 for Rotherham Health Authorities and 8000 for North Nottinghamshire Health. Local logistical factors led to differences in the implementation of the programme by each Health Authority. At the completion of each programme, 8320 doses of vaccine had been administered (92.5 per cent coverage) during the Rotherham Health Authorities programme and 7660 (95.7 per cent coverage) during the North Nottinghamshire Health programme. The additional financial cost of the exercise amounted to approximately Pounds 125000 for each Health Authority. This paper describes the evolution of the outbreak, the decision-making process resulting in the immunization programme in each Health Authority, the implementation of each programme, problems identified and lessons learned.

Application of molecular methods to a nosocomial outbreak of Salmonella enteritidis phage type 4

A nosocomial outbreak of Salmonella enteritidis phage type 4 occurred in July 1995. Seven definite cases were identified over 13 days affecting four wards in a London hospital. The outbreak strain was characterized by plasmid profile typing and pulsed-field gel electrophoresis (PFGE), and was unusual in that it did not possess a 38 MDa plasmid common to most isolates of S. enteritidis PT 4 made from humans and food animals in England and Wales. Seven asymptomatic excreters were identified on screening. No additional cases occurred on wards after standard isolation procedures were implemented. No common or continuing food or dietary source was identified. Results of epidemiological, microbiological and environmental investigations suggested that the outbreak was due to person-to-person transmission within the hospital. The source of the outbreak was not established but was probably due to admission of a patient with an unrecognized infection of S. enteritidis PT 4. The study highlights the importance of close collaboration between hospital staff, epidemiologists and microbiologists, and demonstrates the value of molecular techniques for strain subdivision in outbreak investigations.

An HLA-DR1 transgene confers susceptibility to collagen-induced arthritis elicited with human type II collagen

Rheumatoid arthritis (RA) is an autoimmune disease that is strongly associated with the expression of several HLA-DR haplotypes, including DR1 (DRB1*0101). Although the antigen that initiates RA remains elusive, it has been shown that many patients have autoimmunity directed to type II collagen (CII). To test the hypothesis that HLA-DR1 is capable of mediating an immune response to CII, we have generated transgenic mice expressing chimeric (human/mouse) HLA-DR1. When the DR1 transgenic mice were immunized with human CII (hCII), they developed a severe autoimmune arthritis, evidenced by severe swelling and erythema of the limbs and marked inflammation and erosion of articular joints. The development of the autoimmune arthritis was accompanied by strong DR1-restricted T and B cell responses to hCII. The T cell response was focused on a dominant determinant contained within CII(259-273) from which an eight amino acid core was defined. The B cell response was characterized by high titers of antibody specific for hCII, and a high degree of cross-reactivity with murine type II collagen. These data demonstrate that HLA-DR1 is capable of presenting peptides derived from hCII, and suggest that this DR1 transgenic model will be useful in the development of DR1-specific therapies for RA.

Suppression of murine collagen-induced arthritis by nasal administration of collagen

DBA/1 mice were administered type II collagen (CII) or collagen peptides intranasally before systemic immunization to determine whether tolerance could be induced and autoimmune arthritis suppressed. Although prior experiments have demonstrated that collagen given intravenously or orally is effective, the respiratory mucosal route offers several theoretical advantages for dosing peptides, in addition to ease of use. Intact CII, CB11 and a synthetic peptide containing the immunodominant T-cell epitope recognized by H-2q mice were all effective in reducing the incidence and severity of arthritis and the immune response to CII. Since previous studies have demonstrated the importance of IgG2 antibody subclasses to the induction of collagen-induced arthritis, total immunoglobulin G (IgG), IgG1, and IgG2a and IgG2b were measured. IgG2 antibody subclasses were significantly downregulated by the treatment regimen, whereas a slight decrease in IgG1 antibodies was noted that was not significant. In an effort to determine the mechanism by which arthritis was attenuated, cervical lymph node and spleen cells from treated mice were cultured separately with CII and supernatants tested for the presence of T-cell lymphokines. The cells provided a T-helper 2 (Th2)-like response to CII, with T cells from lymph nodes secreting interleukin-4 (IL-4) and splenocytes secreting both IL-4 and IL-10, whereas a Th1-like response was detected in immunized mice not tolerized with CII. These findings indicate that the downregulation of arthritis that occurs with intranasal administration of CII is associated with Th2-type lymphokine profile and a decrease in complement-fixing antibody subclass.

Management of clusters of meningococcal disease. PHIS Meningococcus Working Group and Public Health Medicine Environmental Group

Guidance on the management of clustered cases of meningococcal disease has been revised following a review of the clusters that occurred in England and Wales between 1 April 1995 and 31 March 1996. Public health action is indicated for confirmed and probable cases but not in response to possible cases. The importance of microbiological confirmation is re-emphasised. Intervention is recommended for defined target groups when two or more confirmed or probable cases occur in a preschool group or school within a four week period. We present a framework to assist in the management of clusters of invasive serogroup C infections in larger and less defined communities.

Marshmallows cause an outbreak of infection with Salmonella enteritidis phage type 4

Thirty-six cases of Salmonella enteritidis phage type (PT) 4 infection, mainly in children, were notified in one local authority in the two weeks beginning on 23 October 1995. Twenty-four cases and 42 controls nominated by cases were included in a case control study, which showed a significant association between illness and the consumption of marshmallow confectionery from a bakery. S. enteritidis PT4 was isolated from samples of the marshmallow, and all isolates had the same plasmid and pulsed field gel electrophoresis profiles. The marshmallow had been made using raw egg white, which shows that not all caterers follow the Department of Health's advice.

Autoantibodies to murine type II collagen in collagen-induced arthritis: a comparison of susceptible and nonsusceptible strains

Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T cells and B cells, and susceptibility is restricted by the class II molecules of the MHC. In this study we identify specific epitopes bound by autoantibodies elicited through immunization of several haplotypes of C57BL/10 mice with chick alpha1 (II)-CB11. ELISA analysis using a panel of 15-mer murine type II collagen peptides revealed a pattern of autoantibody epitope specificity that was remarkably similar among CIA-susceptible and nonsusceptible congenic strains, regardless of class II haplotype. However, one epitope was identified that was bound only by autoantibodies from CIA-susceptible strains bearing I-A(q) (B10.Q and B10.QbetaBR). In addition, this epitope was also present within affinity-purified Ab obtained from the CIA-susceptible strain DBA/1 (I-A(q)). Analyses of immune serum from B10.Q and B10.QbetaBR mice revealed that a subset of the antibodies binding this epitope were of the IgG2 subclass, and therefore efficient at fixing complement, a requirement for pathogenicity of the Abs in CIA.

Autoantibodies to murine type II collagen in collagen-induced arthritis: a comparison of susceptible and nonsusceptible strains

Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T cells and B cells, and susceptibility is restricted by the class II molecules of the MHC. In this study we identify specific epitopes bound by autoantibodies elicited through immunization of several haplotypes of C57BL/10 mice with chick alpha1 (II)-CB11. ELISA analysis using a panel of 15-mer murine type II collagen peptides revealed a pattern of autoantibody epitope specificity that was remarkably similar among CIA-susceptible and nonsusceptible congenic strains, regardless of class II haplotype. However, one epitope was identified that was bound only by autoantibodies from CIA-susceptible strains bearing I-A(q) (B10.Q and B10.QbetaBR). In addition, this epitope was also present within affinity-purified Ab obtained from the CIA-susceptible strain DBA/1 (I-A(q)). Analyses of immune serum from B10.Q and B10.QbetaBR mice revealed that a subset of the antibodies binding this epitope were of the IgG2 subclass, and therefore efficient at fixing complement, a requirement for pathogenicity of the Abs in CIA.

International epidemiological and microbiological study of outbreak of Salmonella agona infection from a ready to eat savoury snack--I: England and Wales and the United States

OBJECTIVES

To identify the source of an international outbreak of food poisoning due to Salmonella agona phage type 15 and to measure how long the underlying cause persisted.

DESIGN

Case-control study of 16 primary household cases and 32 controls of similar age and dietary habit. Packets of the implicated foodstuff manufactured on a range of days were examined for salmonella. All isolates of the epidemic phage type were further characterised by pulsed field gel electrophoresis.

RESULTS

27 cases were identified, of which 26 were in children. The case-control study showed a strong association between infection with S agona phage type 15 and consumption of a peanut flavoured ready to eat kosher savoury snack imported from Israel. S agona phage type 15 was isolated from samples of this snack. The combined food sampling results from the United Kingdom, Canada, the United States, and Israel showed that contaminated snacks were manufactured on at least seven separate dates during a four month period between October 1994 and February 1995. Voluntary recalls of the product successfully interrupted transmission.

CONCLUSIONS

Rapid international exchanges of information led to the identification of the source of a major outbreak of S agona in Israel and of associated cases in North America. The outbreak showed the value of the Salm-Net surveillance system and its links outside Europe, both for increasing case ascertainment and for improving the information on the duration of the fault at the manufacturing plant.

Identification of MHC class II and TCR binding residues in the type II collagen immunodominant determinant mediating collagen-induced arthritis

Collagen-induced arthritis (CIA), an autoimmune arthritis model, is elicited by the immunization of genetically susceptible strains of mice with type II collagen (CII). We have analyzed the molecular interactions that occur during the presentation of the immunodominant determinant within CII(257-270) by the murine class II susceptibility allele, I.Aq. Utilizing a soluble I-A binding assay and clonally distinct CII-specific T cells, we have identified the residues that control the ability of the CII(257-270) peptide to bind to I-Aq and those that interact with the TCR. In competitive binding assays with a panel of analog peptides, only two residues within CII(257-270) were found to participate in the binding of this peptide to I-Aq, residues 260 (Ile) and 263 (Phe). When these substitutions were combined into a single peptide, no binding of the peptide to I-Aq could be detected. Although no other substitutions decreased the binding affinity of the peptides, substitution of several amino acid residues lying outside of the determinant core increased the peptide's affinity for I-Aq and in some instances greatly enhanced the potency of the peptide in stimulating T cells. In antigen presentation assays, clonotypic variation in the recognition of several analog peptides indicated that residues 261, 262, 264, 266, and 267 are likely TCR contact sites. Since residue 266 interacts with the TCR and is the only residue in this determinant that differs between chick/bovine CII and mouse CII, these data indicate that immunity to the autoantigen may play a role in this model.

Antibiotic prescribing during an outbreak of meningococcal disease

During a prolonged outbreak of meningococcal disease caused by serogroup B serotype 15 sulphonamide-resistant strains in one British health district, there was considerable variation in attack rates by town. General practitioner (GP) antibiotic prescribing rates were compared in high and low incidence towns. The only significant difference found was that erythromycin prescribing was more frequent in the high incidence towns (rate ratio 4.0, 95% CI 3.2-4.8, in March 1987 and 3.0, 95% CI 2.4-3.7, in November 1987). This was probably due to increased GP consultation rates for upper respiratory tract infection (URTI), but higher erythromycin usage may have increased meningococcal acquisition rates or susceptibility to meningococcal disease. Antibiotic prescribing rates should be further investigated in defined areas of high and low incidence of meningococcal disease.

Respiratory syncytial virus infection and meningococcal disease

Although viral respiratory tract infections may predispose to meningococcal disease, strong evidence that they do so exists only for influenza. Data on laboratory reported cases of respiratory syncytial virus (RSV) infections and meningococcal disease in England and Wales from mid-1989 to mid-1994 were analysed. Although the rise in RSV cases preceded the rise in meningococcal disease cases each winter, the interval between the rise and fall of the two diseases was inconsistent, no association was found between time series after removal of the seasonal component, and there was no evidence that more cases of meningococcal disease occurred in winters with more RSV disease. RSV may have less effect on the two most likely mechanisms whereby influenza predisposes to meningococcal disease, namely lowered immunity and impaired pharyngeal defences.

Vaccination with a recombinant V alpha domain of a TCR prevents the development of collagen-induced arthritis

A recombinant TCR domain, derived from a T cell hybridoma that recognizes an immunodominant type II collagen epitope, was used to vaccinate against collagen-induced arthritis in DBA/1 (H-2q) mice. The recombinant TCR domain comprises VA11.1-JA17 gene segments and is representative of the V alpha domains expressed by oligoclonal T cells in this disease model. Vaccination of mice 28 days before type II collagen (CII) immunization with this V alpha 11.1 domain resulted in a significantly decreased incidence of arthritis in DBA/1 mice, in contrast to vaccination with a V alpha 4-J alpha 40 domain derived from an encephalitogenic T cell hybridoma specific for MBP. Disease blockade is accompanied by a reduction in T and B cell responses to both the immunogen bovine CII and the autoantigen murine CII. V alpha 4 and V alpha 11.1 domains were found to be highly immunogenic in DBA/1 mice, inducing both T cell proliferation and the production of V alpha specific Abs, indicating that the vaccination effect of V alpha 11.1 is specific. This is the first report of V alpha-directed immunotherapy in an autoimmune disease model and demonstrates the potential use of recombinant TCR vaccines in the treatment of autoimmune diseases that involve oligoclonal autoreactive T cells.

Vaccination with a recombinant V alpha domain of a TCR prevents the development of collagen-induced arthritis

A recombinant TCR domain, derived from a T cell hybridoma that recognizes an immunodominant type II collagen epitope, was used to vaccinate against collagen-induced arthritis in DBA/1 (H-2q) mice. The recombinant TCR domain comprises VA11.1-JA17 gene segments and is representative of the V alpha domains expressed by oligoclonal T cells in this disease model. Vaccination of mice 28 days before type II collagen (CII) immunization with this V alpha 11.1 domain resulted in a significantly decreased incidence of arthritis in DBA/1 mice, in contrast to vaccination with a V alpha 4-J alpha 40 domain derived from an encephalitogenic T cell hybridoma specific for MBP. Disease blockade is accompanied by a reduction in T and B cell responses to both the immunogen bovine CII and the autoantigen murine CII. V alpha 4 and V alpha 11.1 domains were found to be highly immunogenic in DBA/1 mice, inducing both T cell proliferation and the production of V alpha specific Abs, indicating that the vaccination effect of V alpha 11.1 is specific. This is the first report of V alpha-directed immunotherapy in an autoimmune disease model and demonstrates the potential use of recombinant TCR vaccines in the treatment of autoimmune diseases that involve oligoclonal autoreactive T cells.

Identification and characterization of a major tolerogenic T-cell epitope of type II collagen that suppresses arthritis in B10.RIII mice

Tolerization of B10.RIII mice (H-2r) with intravenously injected type II collagen (CII) renders the animals resistant to induction of collagen-induced arthritis (CIA). In order to clarify H-2r-restricted T-cell responses that modulate CIA, we have analysed the T-cell proliferative response of B10.RIII mice against cyanogen bromide (CB) peptides of CII, and detected the strongest response to alpha 1(II)-CB10 (CII 552-897). A panel of chemically synthesized overlapping peptide homologues was used to deduce the minimum structure of this determinant which was found to be CII 610-618. A 15-residue synthetic peptide flanking this region, CII 607-621, was found to effectively suppress arthritis when administered as a tolerogen. Collectively, these data identify the structural component within alpha 1(II)-CB10 which is capable of inducing tolerance in B10.RIII mice. A similar approach to the treatment of autoimmune arthritis, involving the institution of self-tolerance, has potential applicability to human rheumatoid arthritis.

Collagen-induced arthritis in B10.RIII mice (H-2r): identification of an arthritogenic T-cell determinant

Susceptibility to collagen-induced arthritis (CIA), a murine model of autoimmune arthritis, is strongly linked to only two major histocompatibility complex (MHC) haplotypes, H-2q and H-2r. In order to identify the determinants of type II collagen (CII) required to induce arthritis in H-2r-bearing mice, B10.RIII mice were immunized with bovine, chick or human CII. Only bovine CII induced significant arthritis and autoantibodies. When the major CNBr peptides of bovine collagen were isolated and used for immunization, only mice immunized with CB8, representing CII 403-551, developed arthritis. To identify immunogenic epitope(s) within CB8, a panel of synthetic peptides representing overlapping sequences of the bovine peptide was generated. When each peptide was cultured with T cells from B10.RIII mice immunized with CII, one peptide, representing CII 430-466, contained a major T-cell epitope. By using an in vitro lymphokine production assay, the T-cell epitope was further narrowed to CII 442-456. These findings suggest that a T-cell determinant important for the initiation of arthritis in B10.RIII (H-2r) mice is located within a 15 amino acid sequence, residues 442-456 of bovine CII.

Identification and characterization of a tolerogenic T cell determinant within residues 181-209 of chick type II collagen

The murine model of collagen-induced arthritis is characterized by the development of an immune response against joint cartilage. Arthritis can be significantly suppressed by the administration of type II collagen (CII) or one of the CNBr peptides, CB11 (CII 124-402) as a tolerogen prior to immunization. We have previously shown that two synthetic peptides, representing sequences CII 260-270 and CII 181-209, are effective tolerogens. In this paper, we now characterize the T cell determinant with CII 181-209. A series of synthetic peptides overlapping CII 181-209 and analogs of chick CII 181-209 containing site-directed amino acid substitutions was developed and cultured with T cells from DBA/1 mice immunized with CII. Supernatants were collected and analyzed for the presence of the T cell lymphokine IFN-gamma. These data indicate the critical T cell determinant to be located within CII 190-200. This conclusion is further supported by the observation that an unodecapeptide representing CII 190-200 was just as effective as CII 181-209 in suppressing arthritis and anti-CII antibody response when tested as a tolerogen. Analogs containing single amino acid substitutions at residues 191, 194, 197, 198, or 200 were significantly less effective in inducing T cell responses. Each of these peptide analogs was then given as neonatal tolerogens to DBA/1 mice. Mice were subsequently immunized and observed for the development of arthritis. These studies identified residues 194, 197, 198, and 200, and probably residue 191, as critical for tolerance and the suppression of arthritis. Elucidation of the fine structures of T cell determinants which are critical for suppression of arthritis should allow these techniques to be used for developing specific immunotherapeutic approaches to autoimmune arthritis.

Smoking, the environment and meningococcal disease: a case control study

This case control study investigated environmental factors in 74 confirmed cases of meningococcal disease (MD). In children aged under 5, passive smoking in the home (30 or more cigarettes daily) was associated with an odds ratio (OR) of 7.5 (95% confidence interval (CI) 1.46-38.66). ORs increased both with the numbers of cigarettes smoked and with the number of smokers in the household, suggesting a dose-response relationship. MD in this age group was also significantly associated with household overcrowding (more than 1.5 persons per room) (OR 6.0, 95% CI 1.10-32.8), with kisses on the mouth with 4 or more contacts in the previous 2 weeks (OR 2.46, 95% CI 1.09-5.56), with exposure to dust from plaster, brick or stone in the previous 2 weeks (OR 2.24, 95% CI 1.07-4.65); and with changes in residence (OR 3.0, 95% CI 1.0-8.99), marital arguments (OR 3.0, 95% CI 1.26-7.17) and legal disputes in the previous 6 months (OR 3.10, 95% CI 1.24-7.78). These associations were independent of social class. Public health measures to lower the prevalence of cigarette smoking by parents of young children may reduce the incidence of MD. The influence of building dust and stressful life events merits further investigation.

Characterization of the T cell determinants in the induction of autoimmune arthritis by bovine alpha 1(II)-CB11 in H-2q mice

Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T and B cells, and susceptibility is restricted by the class II molecules of the MHC. To study the T cell determinants of bovine type II collagen (CII) that mediate the autoimmune response in H-2q mice, we have identified a cyanogen bromide fragment of bovine CII, CII(124-402), that induces arthritis in DBA/1 mice. Using an overlapping set of peptides to map the T cell response to CII(124-402), we have determined that the I-Aq-restricted T cell response to this collagen fragment is mediated by a single immunodominant antigenic determinant. Consequently, this determinant plays a central role in promoting the production of the collagen-specific Abs and the induction of CIA in H-2q mice. Characterization of this immunodominant determinant revealed that the core residues required for T cell stimulation consists of only eight amino acids and is located at amino acids 260 through 267 of bovine CII. The systematic analysis of the contribution of each of these amino acids, in conjunction with sequences of other peptides known to bind to I-Aq, have allowed us to propose a peptide binding motif for the collagen arthritis susceptibility allele, I-Aq.

Characterization of the T cell determinants in the induction of autoimmune arthritis by bovine alpha 1(II)-CB11 in H-2q mice

Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T and B cells, and susceptibility is restricted by the class II molecules of the MHC. To study the T cell determinants of bovine type II collagen (CII) that mediate the autoimmune response in H-2q mice, we have identified a cyanogen bromide fragment of bovine CII, CII(124-402), that induces arthritis in DBA/1 mice. Using an overlapping set of peptides to map the T cell response to CII(124-402), we have determined that the I-Aq-restricted T cell response to this collagen fragment is mediated by a single immunodominant antigenic determinant. Consequently, this determinant plays a central role in promoting the production of the collagen-specific Abs and the induction of CIA in H-2q mice. Characterization of this immunodominant determinant revealed that the core residues required for T cell stimulation consists of only eight amino acids and is located at amino acids 260 through 267 of bovine CII. The systematic analysis of the contribution of each of these amino acids, in conjunction with sequences of other peptides known to bind to I-Aq, have allowed us to propose a peptide binding motif for the collagen arthritis susceptibility allele, I-Aq.

T cell epitopes of type II collagen that regulate murine collagen-induced arthritis

Chick type II collagen (CII), a protein commonly found in joint cartilage, induces an autoimmune arthritis when administered to susceptible strains of mice. A cyanogen bromide fragment of CII, CB11, contains the requisite epitopes critical for inducing collagen-induced arthritis. If administered as a tolerogen, however, before immunization, CB11 prevents the onset of disease. Therefore, delineation of structural elements of CB11 that can regulate autoreactive T cells became the goal of this study. To delineate the structural elements of CB11 antigenic to T cells, 14 peptides containing overlapping sequences of CB11 were generated. Mononuclear cells from CII-immunized DBA/1 mice were cultured with these peptides and the resulting supernatants examined for the production of IFN-gamma. Two peptides, CII 181-209 and CII 245-270, generated the greatest responses. The ability of these two peptides to regulate arthritis was tested by administering them to neonatal DBA/1 mice as tolerogens before immunization with CII. Both peptides suppressed the incidence of arthritis whereas no other peptide used as a tolerogen significantly altered the course of the disease. T cells from four arthritis-resistant murine strains did not recognize either peptide when immunized with CII, whereas cells from the disease-susceptible B10.Q mice responded well to both. Thus, the coincidence of T cell responses to CII 181-209 and CII 245-270 in CIA-susceptible mice and the lack of response in disease-resistant strains or CII-tolerized mice identify these two peptides as containing important T cell epitopes that regulate CIA.