Immune response inversion after hyperimmunisation. Possible mechanism in the pathogenesis of HLA-linked diseases

Adjuvant effect of dendritic cells activator Imiquimod in genetic immunization with HIV-1 p55 Gag

Dendritic cells (DC) are important antigen-presenting cells that have abilities to induce and maintain T-cell immunity, or attenuate it during hyperimmunization. Additional activation of DCs may be useful for vaccination purposes. Imiquimod is known to be a specific agonist of the Toll-like receptors (TLR7), which are located mainly on DCs. To study the effect of DC stimulation on the effectiveness of an HIV-1 p55 gag DNA vaccine in a mice model, we employed 25, 50, and 100 nM of Imiquimod as an adjuvant. Subsequently, Western blot analysis was used to quantify p55 protein production after the immunization. To characterize T-cells immune response, both the frequency of IFN-γ -secreting cells and IFN-γ and IL-4 production were measured, via an ELIspot assay and ELISA, respectively. Low concentrations of Imiquimod were found to effectively stimulate Gag production and the magnitude of the T-cell immune response, whereas higher concentrations reduced vaccination effects. Our results show that the adjuvant effects of Imiquimod depend on concentration. The use of Imiquimod may be helpful to study DC to T cell communication, including possible induction of immunotolerance.

The role of infectious agents in the spondylarthropathies

The clinical similarities of the spondylarthropathies and their frequent association with both HLA B27 and microbial infections suggest common pathogenetic mechanisms. The latter may include deposition of immune complexes containing bacterial antigens. or cross-reactivity of such antigens with host target tissue or responding cell antigens. Enteric bacteria, chlamydia and mycoplasma are all candidate etiologic agents, but proof is difficult because they are often found as normal flora, although only genetically susceptible individuals may acquire disease, and many patients have been treated with antibiotics before they can be studied. Nonetheless, a role for endogenous bacteria in reactive arthritis at least seems certain, and should stimulate further investigation into similar pathogenetic mechanisms in other chronic arthritides.

A reinvestigation of the cross-reactivity between Klebsiella and HLA-B27 in the aetiology of ankylosing spondylitis

The existence of cross-reactivity between Klebsiella antigens and cells from donors who are HLA-B27 positive and exhibit ankylosing spondylitis (AS) has been reinvestigated. Cells and antisera from different laboratories have been tested together using simultaneously microcytoxicity, chromium release and enzyme linked immunosorbent assays (ELISA). No reproducible interaction has been found. Mitogenic stimulation did not induce cross-reactivity and 'transformation' of B27+AS- cells by Klebsiella culture supernatants failed. Two transformed cell lines from B27+ AS+ donors exhibited specific cross reaction with two anti-Klebsiella antisera but only by chromium release. Immunoprecipitation with these cells and antisera showed the absence of any AS+ -specific antigen. It is concluded that the involvement of Klebsiella in ankylosing spondylitis through simple immunological cross-reactivity or through interaction with HLA-B27 is unlikely.

Identification of HLA-B27M1 and -M2 cross-reactive antigens in Klebsiella, Shigella and Yersinia

Images

Infection and chronic rheumatic disease in children

It is clear that various microbial agents can cause acute and chronic rheumatic disease by several mechanisms, that different agents, some perhaps yet unknown, may cause the same disease in different patients, and that genetic factors are important, perhaps crucial, to this host response. In trying to elucidate how microbe-host interactions result in chronic rheumatic disease, interest currently centers on the roles of genetic factors, of bacterial infections including endogenous flora, of cross-reactive microbial and host antigens, and of the immune response to them. As in the past, progress in understanding these complex interactions will probably be incremental and intermittent.

Frequency of faecal Klebsiella aerogenes in patients with ankylosing spondylitis and controls with respect to individual features of the disease

A study of 59 patients with definite ankylosing spondylitis and 41 comparable hospital outpatients with fractures has been undertaken to determine if the presence of faecal Klebsiella aerogenes is related to clinical activity of the spinal disease and its extraspinal features. The frequencies of fecal K. aerogenes were similar in both patients and controls and were not significantly related to spinal disease activity. Careful inquiry about antibiotic treatment, dietary habits, and hospitalisation did not significantly influence the results. A significant association was found between the presence of faecal K. aerogenes and both acute non-granulomatous anterior uveitis (P less than 0.01) and peripheral synovitis in HLA B27 positive patients (P less than 0.05). These results suggest that K. aerogenes may have an aetiological role in the development of non-granulomatous anterior uveitis and peripheral arthritis in patients with ankylosing spondylitis but do not lend support to this organism having such a role in the spinal disease itself.

C-reactive protein, ESR, and klebsiella in ankylosing spondylitis

Serum C reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured on 469 occasions in 149 patients with ankylosing spondylitis who had also been investigated for faecal carriage of klebsiella/enterobacter species on the same occasions. Raised values of CRP and ESR correlated with each other (P less than 0.001) as well as with clinically assessed active disease episodes (P less than 0.001). Patients with positive cultures for klebsiella were found to have higher mean values for CRP and ESR than those with negative cultures (P less than 0.025). CRP appears to be a useful marker of disease activity in ankylosing spondylitis.

Ankylosing spondylitis, HLA-B27 and Klebsiella. I. Cross-reactivity studies with rabbit antisera

Sera from rabbits immunized with HLA-B27 lymphocytes showed increased activity against klebsiellal enterobacter antigens using immunodiffusion, bacterial agglutination (P less than 0.025), haemagglutination (P less than 0.001) and radiobinding assays (P less than 0.001). Immunoprecipitin lines were also produced by these antilymphocyte sera against extracts from Yersinia enterocolitica and Shigella sonnci microorganisms. Rabbit anti-klebsiella sera had lymphocytotoxic activity against HLA-B27 lymphocytes obtained from patients with ankylosing spondylitis (P less than 0.001). These results suggest partial cross-reactivity between some antigens found in several Gram-negative microorganisms and HLA-B27 lymphocytes.

Sequential studies in ankylosing spondylitis. Association of Klebsiella pneumoniae with active disease

A study of 163 patients with ankylosing spondylitis seen on 433 occasions showed that active inflammatory disease was strongly associated with the presence of Klebsiella pneumoniae in the faeces (P less than 0.001). Sequential studies showed that in patients with inactive disease the presence of a positive culture for Klebsiella was associated with the subsequent development of active inflammatory disease (P less than 0.001). These findings support the hypothesis that Kl. pneumoniae may be an initiating agent in ankylosing spondylitis.