Intestinal secretory immunoglobulin A response to enteroaggregative Escherichia coli in travelers with diarrhea.

We examined stool samples from travelers for secretory immunoglobulin A (sIgA) to enteroaggregative Escherichia coli (EAEC) during episodes of acute diarrhea. Ten paired samples from 10 patients with diarrhea caused by EAEC were examined for the presence of specific sIgA by dot blot and Western blot immunoassays. Five samples were positive by dot blotting, and two samples were positive by Western blotting.

Myelin- and microbe-specific antibodies in Guillain-Barré syndrome.

We surveyed the frequency of reported infections and target autoantigens in 56 Guillain Barré syndrome (GBS) patients by detecting antibodies to myelin and microbes. Sulfatide (43%), cardiolipin (48%), GD1a (15%), SGPG (11%), and GM3 (11%) antibodies were the most frequently detected heterogenous autoantibodies. A wide spectrum of antimicrobial IgG and IgM antibodies were also detected; mumps-specific IgG (66%), adenovirus-specific IgG (52%), varicella-zoster virus-specific IgG (46%), and S. pneumoniae serotype 7-specific IgG (45%) were the most prevalent. Our results indicate that polyclonal expansion of physiologic and pathologic antibodies and/or molecular mimicry likely occurs following infection and is related to other autoimmune factors in the etiology of GBS. Although no single definitive myelin-specific autoantibody was identified, our results suggest a unique pattern of reactivity against autoantigens.

Autoantibody profile of primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic progressive liver disease of unknown etiology. It has been suggested that genetic and immunological factors are important in its pathogenesis. The present study examined the prevalence of 23 different autoantibodies in 25 PSC sera, by ELISA, in order to better define the autoimmune profile of PSC. The results indicate that 88% of PSC patients produced at least 1 autoantibody, and 36% had reactivity to multiple autoantibodies. Moreover, 35% of the PSC patients produced anti-endothelial-cell antibodies (AECA) and 75% of the sera contained perinuclear antineutrophil cytoplasmic antibodies (pANCA), detected by indirect immunofluorescence. The prominent ANCA autoantibody was anti-cathepsin-G, demonstrated in 35% of the patients. The multiplicity of the autoantibody profile, revealed in the present study, points to the autoimmune characteristics of PSC. In addition, the association of ANCA and of AECA in PSC may suggest a pathogenic role for these antibodies in PSC.

The H3 anti-phospholipid idiotype is found in patients with systemic lupus erythematosus (SLE) but not in patients with syphilis.

The human H3 idiotype, defined by a mouse monoclonal antibody S2.9, is commonly found in patients with SLE where it is correlated with the amount of anti-cardiolipin antibodies. No correlation between the amount of anti-cardiolipin antibody and the H3 idiotype is found in patients with syphilis. Using the S2.9 antibody, serum from each of 10 patients with SLE and eight patients with syphilis was separated into H3-bearing and H3-negative fractions. Comparison of the partition of anti-cardiolipin antibody in these two groups of patients revealed that much of the anti-cardiolipin antibody (44-91%) was found in the H3+ fraction in patients with SLE; in patients with syphilis, virtually none of the anti-cardiolipin antibody was H3+. In patients with SLE, the H3+ fraction contained both IgG and IgM and antibodies of both kappa and lambda light chains. The H3+ fraction was polyspecific and frequently reacted with dsDNA.

A common anti-cardiolipin antibody idiotype in autoimmune disease: identification using a mouse monoclonal antibody directed against a naturally-occurring anti-phospholipid antibody.

We have recently produced a series of human monoclonal antibodies reacting with cardiolipin. One of these, H3, a polyspecific IgM/k derived from a normal individual, was used to raise mouse monoclonal antibody to its idiotype. Two anti-idiotypic antibodies, S2.9 (IgG2b) and S2.10 (IgM) were selected for their specific reaction with H3.S2.9 did not react with five other human monoclonal antibodies of IgM/k class despite the fact that these shared some antigen-binding characteristics with H3.S2.9 was able to block the binding of H3 to all of its cross-reactive antigens including cardiolipin, while S2.10 was not. S2.9 was equally efficient in blocking the binding of H3 to three of its cross-reactive antigens, cardiolipin, diphtheria and tetanus toxoids; greater than 90% inhibition could be achieved at an equimolar ratio of H3 to S2.9. The anti-idiotype S2.9 was used to demonstrate the presence of the H3 idiotype in serum. This idiotype was found in amounts greater than that seen in 42 normal individuals, in 30 of 36 patients with systemic lupus erythematosus (SLE), eight of 20 patients with rheumatoid arthritis (RA), 8 of 20 patients with Felty's syndrome as well as 10 of 23 patients with syphilis. Not one of nine patients with drug-induced lupus syndrome had abnormal levels. In patients with SLE and Felty's syndrome there was a good correlation between the amount of anti-cardiolipin antibodies and the amount of H3 idiotype (rs = 0.70 and 0.69 respectively). No such correlation was found in syphilitics or in patients with RA. In patients with SLE the H3 idiotype was present on IgM and IgG anti-cardiolipin antibodies. In 15 of 16 SLE sera with high levels of cardiolipin antibody, S2.9 blocked binding of serum antibodies to cardiolipin by 13-72%, with a mean value of 49%. One patient had a high level of anti-cardiolipin antibody which could not be blocked by S2.9. These results indicate that a mouse monoclonal antibody which reacts with an idiotope in the antigen-binding region of a naturally-occurring phospholipid antibody also defines a common idiotype of anti-cardiolipin antibodies in patients with autoimmune disease.

Microplate ELISA for detection of antibodies to DNA in patients with systemic lupus erythematosus: specificity and correlation with Farr radioimmunoassay.

A 96-well microplate ELISA for the detection of antibodies to DNA is described. A number of buffers and precoating treatments were used to evaluate the optimal method for coating the plate with DNA. These included pretreatment of the plates with poly-L-lysine or protamine sulfate, and posttreatment with glutaraldehyde, none of which improved the performance of the assay. Whereas bicarbonate and borate coating buffers gave equivalent and satisfactory results, TRIS buffer resulted in very high binding of immunoglobulin to wells not coated with antigen. Sera from groups of patients with autoimmune disease as well as normal sera were tested against plates optimally coated with native E. coli DNA, calf thymus DNA, and heat-denatured DNA. Using native E. coli DNA, virtually none of 35 normal sera had any detectable antibody. With this antigen, as well as with native calf thymus DNA, significant levels of DNA antibody were found only in SLE patients. Most patients with SLE or drug-induced lupus, as well as some patients with rheumatoid arthritis and normal individuals had antibodies that bound to heat-denatured (single-stranded) DNA. Using either native E. coli or calf thymus DNA, a good correlation was found between the amount of DNA antibody detected by ELISA and the Farr-type radioimmunoassay.

Polyspecific human and murine antibodies to diphtheria and tetanus toxoids and phospholipids.

Human-human hybridomas produced from lymphocytes of normal individuals yielded seven clones producing monoclonal antibody reacting with tetanus toxoid. Three of these antibodies cross-reacted with diphtheria toxoid. These three and two others also reacted with cardiolipin and two with other phospholipids. One of the seven antibodies reacted with tetanus and diphtheria toxoids, cardiolipin and single-stranded DNA. All seven antibodies were IgM. To examine further this unusual cross-reactivity serum antibodies from patients with SLE and healthy individuals were affinity-purified to yield diphtheria toxoid antibodies. Six out of nine of these anti-diphtheria preparations contained IgG antibodies which cross-reacted with tetanus toxoid and two of these also reacted with cardiolipin; four preparations cross-reacted with DNA. Anti-cardiolipin and anti-DNA cross-reactivity were found in preparations from both normal and SLE sera. Similar cross-reactivities were demonstrated using four mouse monoclonal IgM antibodies raised against phospholipids. All four of these antibodies reacted with both cardiolipin and tetanus toxoid and two also reacted with diphtheria toxoid and DNA. Using a thiocyanate elution procedure, it was shown that the cross-reactivity of the monoclonal antibodies was not related to their relative affinities. The results clearly indicate that cross-reactive epitopes occur on routinely used toxoid vaccines and self antigens. Antibodies which bind to these cross-reactive epitopes are common and are not restricted in isotype, affinity or species of origin.