Antibody repertoire against culture filtrate antigens in wild house mice infected with Mycobacterium bovis BCG

Autoreactive antibodies are present in sheep with Johne's disease and cross-react with Mycobacterium avium subsp. paratuberculosis antigens

Mycobacterial infection has been linked to the generation of autoantibodies, including anti-neutrophil cytoplasmic autoantibodies (ANCA), in clinical studies and small animal models. In an attempt to identify antibodies that react with both self and mycobacterial antigens in naturally infected ruminants, we generated a phage display library comprising single chain antibody fragments (scFv) from sheep with Johne's disease (JD). The library was screened simultaneously against ovine small intestinal tissue and Mycobacterium avium subsp. paratuberculosis (MAP). A clone (termed AutoH1) reacted strongly with host tissue and MAP, recognizing a proteinase-susceptible 32 kDa determinant in ovine gut tissues and lymphatics, and in blood granulocytes but not mononuclear cells. In granulocytes, binding was to cytoplasmic granules and cell membranes; in MAP, AutoH1 bound bacterial cell wall determinants. We further identified a synthetic peptide sequence recognized by AutoH1, using this to generate a carrier:peptide fusion protein (paH1). Sera of normal and JD sheep were screened for AutoH1-like autoantibody activity; 7/11 JD animals showed autoreactivity that could be blocked by paH1, while 0/21 normal animals showed no such serological reactivity. It is possible that the severe pathology observed in ruminant JD may have an autoimmune component, possibly due to ANCA-type binding; this remains to be further investigated.

Tuberculosis antigen A60 serodiagnosis in tuberculous infection: application in extrapulmonary and smear-negative pulmonary tuberculosis

An ELISA diagnostic test for tuberculosis antigen A60 (TBA60) IgG/IgM was used in a tertiary referral hospital in Taiwan. From June 1992 to December 1993, serum samples obtained from 907 patients were analyzed for TBA60 IgG and IgM titres. The final diagnosis of these patients was confirmed by microbiological study and clinical follow up for 18-24 months. Among 147 patients with active pulmonary tuberculosis, IgG was positive in 112 (76.2%), IgM was positive in 14 (9.52%). Among 90 patients with active extrapulmonary tuberculosis, IgG was positive in 53 (58.9%), IgM was positive in 9 (10%). Among 153 patients with inactive tuberculosis, IgG was positive in 28 (18.3%), IgM was positive in 1 (1.6%). Among 517 patients with nontuberculous disease, IgG was positive in 50 (9.7%), IgM was positive in 3 (0.6%). In this study population with 26% (237/907) active tuberculous infection rate, the TBA60 ELISA IgG had a diagnostic sensitivity of 69.6% and a specificity of 92.1%. These results indicate a positive predictive value of 67.9% and a negative predictive value of 89.2%. The sensitivity of IgM was 10.5% and specificity, 99.4%. The serum IgG tire had good correlation with the extent of pulmonary TB had a higher percentage of IgG seropositivity (83.9%) than those with smear-negative pulmonary TB (70.6%) and extrapulmonary TB (58.9%). In 50 cases with active tuberculosis, follow-up examinations were carried out one month after treatment. In 18 cases with initially negative IgG and IgM titres, 13 showed elevation of serum IgG titres into positive level, one had positive seroconversion of IgM which was the only serological marker indicating active infection. Therefore, 77.8% (14/18) gained diagnostic benefit from follow-up serological examination. It was concluded that TBA60 IgG and IgM ELISA is a useful test when diagnosing tuberculosis. This test also assists in the clinical judgement of tuberculosis when used as an adjunct to symptoms and sputum smear, and for monitoring therapeutic response at the commencement of treatment.

Influence of genes from the major histocompatibility complex on the antibody repertoire against culture filtrate antigens in mice infected with live Mycobacterium bovis BCG

C57BL/10 and C57BL/6 mice (H-2b); B10 congenic mice with f, k, p, q, r, and s H-2 haplotypes; B10 mice with recombinant g2, o2, a, h2, h4, i5, and bq1 H-2 haplotypes; and B6 mice with major histocompatibility complex (MHC) mutant bm1 and bm13 (class I) and bm12 (class II) haplotypes were infected intravenously with 4 x 10(6) CFU of live Mycobacterium bovis BCG and examined by Western immunoblot analysis for serum antibodies against BCG culture filtrate antigens, following a boost injection with live BCG or with BCG culture filtrate. Parental B10 and B6 mice reacted very intensely with three culture filtrate protein bands with estimated molecular masses of 37, 38, and 40 kDa. Response against the 40-kDa protein was stronger following a boost injection with live BCG than following a boost with culture filtrate. Sera from mice with f, p, i5, bm1, and bm13 haplotypes reacted strongly, with both the 37-38- and 40-kDa antigens, and sera from mice with q and bq1 haplotypes showed a somewhat weaker reaction. Sera from mice with r, s, and bm12 haplotypes reacted against the 37-38-kDa antigen but not against the 40-kDa antigen, and sera from mice with the h2 haplotype reacted only with the 40-kDa antigen but not with the 37-38-kDa antigen. Sera from mice with the k, g2, o2, a, and h4 haplotypes showed, at most, a very weak reaction with the 37-38- and 40-kDa antigens. These results demonstrate that MHC genes profoundly affect the antibody repertoire used against culture filtrate antigens in mice infected with live M. bovis BCG. In particular, as shown in mice with the recombinant H-2 haplotype and in class II mutant bm12 mice, the I-A heterodimer controls the recognition of the immunodominant 40-kDa antigen. By using crossed immunoelectrophoresis, this 40-kDa antigen was identified as antigen 88 according to the reference system of Closs et al. for BCG antigens.

Towards an understanding of the mode of action of Bacillus Calmette-Guérin-therapy in bladder cancer treatment, especially with regard to the role of fibronectin

The interaction between Bacillus Calmette-Guérin (BCG) and the host was investigated after repeated intravesicular BCG-therapy for superficial bladder cancer. Studies were performed on (a) the local reaction in the bladder, (b) the systemic reaction, and (c) short and long term interactions in both the bladder and the serum/plasma. The analytes measured included anti-BCG IgA and IgG, fibronectin, lactoferrin, elastase-alpha 1-proteinase inhibitor, myeloperoxidase and alpha 2-proteinase inhibitor. All analytes, with the exception of alpha 2-proteinase inhibitor, were measured in both serum/plasma and urine. An additional group of 94 patients undergoing bronchoalveolar lavage was used for comparison with other diseases affecting mucous membranes. In vitro studies on human bladder in culture were also carried out to study the relationship between BCG, elastase and fibronectin. The results revealed a normal defence reaction, in which IgA and IgG antibodies specific to BCG were produced by the host. Maximal concentrations of all analytes in urine were found about 4 h after BCG instillation. Immunoglobulins, soluble fibronectin, and granulocyte markers all appeared in urine after instillation and all showed a similar time course. The in vitro study showed the synergistic effect of elastase and BCG in stimulating the host defence reaction. The relationship between BCG and fibronectin can be seen as fortuitous but not indicative of the efficacy of BCG-therapy in patients with superficial bladder cancer.

Antibodies against secreted and non-secreted antigens in mice after infection with live Mycobacterium tuberculosis

Mice from four different inbred strains were infected with live Mycobacterium tuberculosis and the immune response to M. tuberculosis was followed for 24 weeks, using Western blotting. Nearly all mice, irrespective of H-2 type, reacted with the 38-kDa protein band. Antibodies against this secreted 38-kDa protein were the first to appear, 4 weeks after infection. Thereafter the secreted 19-kDa protein and non-secreted antigens, such as the 65-kDa and 33-kDa proteins, were recognized. The immune response against the non-secreted antigens was influenced by the mouse strain. However, the 33-kDa protein band was recognized by all mouse strains after a second injection with live M. tuberculosis. The specificity of the antibodies was analysed in Western blot using sonicates of M. tuberculosis, M. kansasii, M. avium, M. terrae, M. gordonae and Escherichia coli. Antibodies against the 38-kDa and 33-kDa protein bands seemed to be specific for M. tuberculosis, while antibodies against the 19-kDa protein band showed limited cross-reactivity. Antibodies against the 65-kDa protein were strongly cross-reactive. These results suggest that the 38-kDa protein is secreted in vivo and, therefore, may be available to the humoral immune system at an early stage of infection. The non-secreted 33-kDa protein is only recognized by all mouse strains after prolonged contact with M. tuberculosis.

The humoral immune response to heat shock proteins

Humoral immune reactions to heat shock proteins (hsp) from microorganisms are one aspect of microbial infections in humans. The production of antibodies which are specific to epitopes present on procaryotic hsp leads also to the appearance of cross-reactive serum antibodies in the host organism that react with human hsp. This article discusses the consequences of such autoreactive antibodies for the host in context with the development of immune tolerance and autoimmune diseases, especially rheumatoid arthritis (RA), and in experimental animal models for arthritis such as adjuvant arthritis in rats. On the basis of epitope cross-reactivity between hsp and other host proteins, a hypothesis is presented for the development of autoimmune disease following the production of hsp-specific antibodies.