Lupoid sclerosis: a possible pathogenetic role for antiphospholipid antibodies

The case of a 45-year-old woman is described who developed transverse myelitis over a one-year period. Serological tests suggested a lupus-like illness. Antibodies to cardiolipin of the IgM class were detected in high titres in her serum. These may have played a part in the pathogenesis of her disease.

Common IgA and IgM rheumatoid factor idiotypes in autoimmune diseases

Anti-idiotypic antibodies to four monoclonal IgM, one polyclonal IgM, and one polyclonal IgA rheumatoid factors were produced in rabbits and tested for cross reactivity with rheumatoid factors from nine patients with essential mixed cryoglobulinaemia, three patients with rheumatoid arthritis, four patients with systemic sicca syndrome, and one patient with systemic lupus erythematosus. Variable (3/16 to 10/16) cross reactivity for each anti-idiotypic antibody was observed which was not restricted by disease category, clonality, or isotype of the rheumatoid factor. These findings suggest that rheumatoid factor genes are highly conserved from the germ-line antibody repertoire.

Crossreactivity of antiphospholipid antibodies

Using a solid phase radioimmunoassay to detect anticardiolipin antibodies, the crossreactivity of these antibodies with phospholipids and DNA was tested in 10 patients with autoimmune disorders and 1 patient with secondary syphilis. The crossreactivity of anti-ds DNA and anti-ss DNA antibodies with cardiolipin was tested in 10 additional patients with SLE. In the 10 sera tested with high anticardiolipin antibody levels, there was marked inhibition of anticardiolipin antibody activity by negatively charged phospholipids. The zwitterionic phospholipids inhibited anticardiolipin antibody activity in some sera, and in instances where this occurred, inhibition was less than that obtained for the negatively charged phospholipids. There was minimal inhibition of anticardiolipin antibody by ss DNA in only 2 of 10 sera tested and no inhibition by ds DNA in any sera tested. Conversely, cardiolipin inhibited anti-ss DNA antibody activity in 2 of 10 sera, and anti-ds DNA antibody activity in 2 of 10 sera tested. There was no correlation between anticardiolipin antibody levels and either anti-ds DNA or anti-ss DNA antibody levels. These results suggest that antiphospholipid and anti-DNA antibodies are largely separate groups of antibodies. On the basis of these studies, we suggest that there may be various groups of antiphospholipid antibodies in patients with SLE and other autoimmune disorders.

Anticardiolipin antibodies: detection by radioimmunoassay and association with thrombosis in systemic lupus erythematosus

A new solid-phase radioimmunoassay for the detection of anticardiolipin antibodies is 200-400 times more sensitive than the precipitation method used in the Venereal Disease Reference Laboratory test. 61% of serum samples from patients with systemic lupus erythematosus (SLE) had high levels of anticardiolipin antibodies of at least one immunoglobulin class. There were strong correlations between raised anticardiolipin levels and the lupus anticoagulant, venous and arterial thrombosis, and thrombocytopenia, but no correlation with anti-DNA antibody levels. Of the 15 patients with the highest anticardiolipin titres, 6 had a history of venous thrombosis, 5 cerebral thrombosis, 5 thrombocytopenia, and 2 each pulmonary hypertension and multiple abortions. This simple immunoassay appears to have predictive value for thrombosis in SLE and related disorders.

IgA and IgM rheumatoid factors in serum, saliva and other secretions: relationship to immunoglobulin ratios in systemic sicca syndrome and rheumatoid arthritis

Paired serum and saliva samples from seven patients with systemic sicca syndrome (SSS), 15 patients with rheumatoid arthritis and a positive Schirmer's test (RA+), 15 patients with rheumatoid arthritis and negative Schirmer's test (RA-) and 14 normal individuals were analysed for albumin and immunoglobulin concentration as well as IgA and IgM rheumatoid factor (RF) activity. Protein levels in saliva were higher in SSS and RA+ but, when corrected for serum concentration and salivary flow rate, only the IgG ratio remained significantly elevated in SSS (P less than 0.01) and RA- (P less than 0.05) and the IgM ratio was reduced in RA- (P less than 0.05) compared to controls. Although IgM RF activity in serum and saliva was strongly correlated (P less than 0.001) in all three patient groups, the activity in saliva was considerably lower than serum activity. In the two (RA) patients tested, IgM RF in saliva contained secretory component. Mean salivary IgA RF activity varied between 34% (RA-) and 84% (SSS) of serum activity and correlated with serum activity in SSS (P less than 0.001) and RA- (P less than 0.01). IgA RFs in saliva, but not in serum, contained secretory component. Additional demonstration of IgA RF activity in nasal and duodenal secretions in SSS may be related to involvement of the common mucosal immune system.

Enhancement of cryoprecipitation from hypotonic serum: a comparative study in normals and in patients with connective tissue diseases

In a study of 17 normals and 26 patients we have established a normal range for cryoglobulins in a standard and a simple hypotonic system. In a comparison of standard and hypotonic cryoprecipitates in patients with connective tissue diseases we showed a significant increase in protein content (p less than 0.001), IgM (p less than 0.01) and IgM rheumatoid factor (p less than 0.01) in the hypotonic samples. The ratios of IgM RF/IgM in hypotonic cryoglobulins compared to standard cryoglobulins were significantly increased as shown by a chi 2 analysis in both normals (p less than 0.05) and patients (p less than 0.01). Estimation of cryoglobulins in a hypotonic system is a useful simple test which may detect distinct groups of proteins and rheumatoid factors. Precipitates were demonstrated in patients who had previously been considered serologically normal.

Radioimmunoassay profile of antiglobulins in connective tissue diseases: elevated level of IgA antiglobulin in systemic sicca syndrome

A microplate radioimmunoassay for IgG, IgA and IgM antiglobulins reactive with rabbit IgG was performed on sera from 69 patients with various connective tissue diseases. IgM antiglobulins were detected in rheumatoid arthritis, systemic sicca syndrome and some patients with systemic vasculitis. IgA antiglobulins were found in seven of 10 patients with systemic sicca syndrome and only five of 59 patients with other connective tissue diseases. There was no correlation between the levels of IgM and IgA antiglobulins in the systemic sicca syndrome or rheumatoid arthritis (r = -0.21 and 0.2 respectively). IgG antiglobulins were not detected in any serum which lacked IgM or IgA antiglobulins. IgG isolated by DEAE columns showed antiglobulin activity in six of 15 rheumatoid arthritis and two of 10 systemic sicca syndrome sera tested. Antiglobulin analysis of sera fractionated by sucrose density ultracentrifugation at neutral and acid pH enabled the size of each class of antiglobulin to be determined. In certain sera, antiglobulin activity extended into the denser region of the gradient at pH 7.2 suggesting that the antiglobulins were complexed.