SummaryLewis rats are susceptible to several forms of experimental arthritis-induced using heat-kiUed MFobacterium tuberculosis (adjuvant arthritis, or AA), streptococcal cell walls, collagen type II, and the lipoidal amine CP20961. Prior immunization with the mycobacterial 65-kD heat shock protein (hsp65) was reported to protect against AA, and other athritis models not using M. tuberculosis, via a T cell-mediated mechanism. Hsp65 shares 48% amino acid identity with mammalian hsp60, which is expressed at elevated levels in inflamed synovia. Several studies have reported cross-reactive T cell recognition of mycobacterial hsp65 and self hsp60 in arthritic and normal individuals. We previously described nine major histocompatibility complex class II-restricted epitopes in mycobacterial hsp65 recognized by Lewis rat T cells. Of these only one, covering the 256-270 sequence, primed for cross-reactive T cell responses to the corresponding region of rat hsp60. Here we have tested each hsp65 epitope for protective activity by immunizing rats with synthetic peptides. A peptide containing the 256-270 epitope, which induced cross-reactive T cells, was the only one able to confer protection against AA. Similarly, administration of a T cell line specific for this epitope protected against AA. Preimmunization with the 256-270 epitope induced T cells that responded to heat-shocked syngeneic antigen-presenting cells, and also protected against CP20961-induced arthritis, indicating that activation of T cells recognizing an epitope in self hsp60 can protect against arthritis induced without mycobacteria. Therefore, in contrast to the accepted concept that cross-reactive T cell recognition of foreign and self antigens might induce aggressive autoimmune disease, we propose that cross-reactivity between bacterial and self hsp60 might also be used to maintain a protective self-reactive T cell population. This discovery might have important implications for understanding T cell-mediated regulation of inflammation.A the pathogenic mechanisms underlying rheumatoid arthritis (RA) remain unclear, extensive use is made of experimental rodent arthritis models. Lewis rats are susceptible to arthritis after administration of various arthritogenic preparations including heat-killed Mycobacterium tuberculosis (Mt) 1 suspended in IFA (adjuvant arthritis, or AA) (1) streptococcal cell walls (SCW-arthritis) (2), collagen type II (3), and the lipoidal amine CP20961 (4).The antigenic epitope recognized by the arthritogenic T cell clone A2b (generated from a rat with AA) was identified as residues 180-188 of the 65-kD mycobacterial heat shock 1 Abbreviations used in this paper: AA, adjuvant arthritis; DDA, dimethyl dioctadecyl ammonium bromide; hsp65, mycobacteria165-kD heat shock protein; hsp60, mammalian 60-kD heat shock protein; M.256-270, synthetic peptide of mycobacterial hsp65 256-270 sequence; Mt, heat-killed Mycobacterium tuberculosis; PLNC, primed lymph node cell; R.256-270, synthetic peptide of rat hsp60 256-270 sequence. 943 protein (hsp6...

Adjuvant arthritis (AA) is a chronic disease inducible in rats by immunization with an antigen of Mycobacterium tuberculosis. After the isolation of arthritogenic T-cell lines and clones, it became possible to demonstrate that the critical M. tuberculosis antigen contained an epitope cross-reactive with a self-antigen in joint cartilage. Like AA rats, patients suffering from rheumatoid arthritis demonstrated specific T-lymphocyte reactivity to the M. tuberculosis fraction containing the cross-reactive epitope. To characterize the critical M. tuberculosis epitope we used AA T-cell clones to screen mycobacterial antigens expressed in Escherichia coli and genetically engineered truncated proteins and synthetic peptides. The AA T-cell clones recognized an epitope formed by the amino acids at positions 180-188 in the sequence of a Mycobacterium bovis BCG antigen. Administration of this antigen to rats induced resistance to subsequent attempts to produce AA.

Serum samples and immunoglobulin fractions of eight mammalian species were applied to a Sepharose--protein A column. As with the human immunoglobulin subclasses IgG1, IgG2 and IgG4, all examined IgG classes and subclasses were bound to a greater or lesser extent to protein A. However, the binding of IgG1 of ruminants was very poor. Polyclonal IgM and IgA of the pig, the dog and the cat may be separated in protein A reactive and protein A non-reactive fractions. In addition, monoclonal canine IgM and IgA partially reacted with protein A. In combination with methods such as ammonium sulphate precipitation, ion exchange chromatography and gel-filtration, affinity chromatography with protein A is recommended for the rapid purification of certain Ig (sub)classes of a number of mammalian species.

One-day-old chickens with maternally derived antibodies to infectious bronchitis virus (IBV) were vaccinated against IB by eye-drop. At 2 and 3 weeks of age the synthesis of immunoglobulins of the IgA isotype in the Harderian gland was demonstrated by immunofluorescence. With an anti IgG conjugate diffuse fluorescence of IgG was observed in the gland at 2, 3 and 4 weeks of age. Involvement of the Harderian gland in the synthesis or the secretion of IgM after IB vaccination could not be demonstrated by immunofluorescence. A quantitative estimation of immunoglobulins was carried out by laser nephelometry. At 2 weeks of age the concentration of antibodies against IBV of the IgA isotype (IgA-IBV) was higher in the tears than in the serum. This and the positive fluorescence indicate a local synthesis of IgA-IBV in the Harderian gland. The highest concentration of IgG antibodies against IBV (IgG-IBV) in the serum was measured at 2 weeks of age, when IgG antibodies could not be detected in the tears. In the tears the IgG-IBV concentration increased from 2 weeks up to and including 5 weeks of age, when the concentration in the tears was higher than in the serum. These findings and the diffuse IgG fluorescence in the Harderian gland suggest a mainly systemic production of IgG-IBV and an active and selective transport of IgG-IBV from the serum to the tears by the Harderian gland. Challenge at 6 weeks of age of the vaccinated chicks caused a sharp increase of IgG-IBV in the serum and a decrease of IgA-IBV in the tears 1 week later. Challenge of the unvaccinated control chicks resulted in a distinct rise of IgA-IBV in the tears and in a low IgG-IBV concentration in the serum after 1 week. These findings and the neutralisation indices measured for sera collected at 5 and 7 weeks are discussed.

No abstract