Anti-phospholipid and anti-mitochondrial type M5 antibodies in systemic lupus erythematosus

Fifty-one sera from patients with systemic lupus erythematosus (SLE) were studied in order to evaluate the prevalence of anticardiolipin (ACA) and anti-mitochondrial antibodies (AMA) type M5, and also to explore their relationship with the main serological and clinical features of the disease. A group of 25 (49.0%) patients was found to be ACA positive (IgG or IgG and IgM); in this group we found a significantly higher prevalence of false positive VDRL (p less than 0.01), lupus-like anticoagulant (p less than 0.05), and AMA type M5 (p less than 0.01), but not of anti-ds or ss-DNA antibodies. Three sera positive for ACA, AMA-M5 and anti ss-DNA were absorbed with cardiolipin liposomes. Anti-DNA and AMA-M5 showed only a minimal decrease. Central nervous system involvement and especially seizure syndrome was demonstrated with a higher prevalence in ACA-positive groups (p less than 0.05). Despite the results of absorption experiments, the close relationship between AMA-M5 and ACA, false positive VDRL or lupus-like anticoagulant (LLAC) might justify a speculation on the antiphospholipid nature of this antimitochondrial activity.

Affinity purified anti-cardiolipin and anti-DNA antibodies

Recent studies have raised questions concerning the specificity of anticardiolipin antibodies and their relationship to anti-DNA antibodies, the lupus anticoagulant, the biological false positive test for syphilis, and reagin, the antibody detected in syphilis. In an attempt to answer some of these questions, 3 IgG and 2 IgM affinity purified anticardiolipin antibodies, as well as 3 affinity purified anti-DNA antibodies were studied. Affinity purified anti-cardiolipin antibodies showed high binding to negatively charged phospholipids but not to ssDNA by solid phase radioimmunoassay. On the other hand, affinity purified anti-DNA antibodies did not bind cardiolipin. Inhibition experiments showed that negatively charged phospholipids and VDRL liposomes inhibited the binding of anticardiolipin antibodies to phosphatidylserine, but ssDNA, alpha-glycerol phosphate and hyaluronic acid did not. Similar studies of sera from patients with high anticardiolipin antibody levels supported the results obtained with affinity purified anticardiolipin antibodies. These results suggest that anticardiolipin antibodies bind negatively charged phospholipids and there appears to be little crossreactivity with DNA or unrelated negatively charged polymers such as hyaluronic acid. Both the negatively charged phosphodiester group and glyceride portions of the phospholipid molecules appear important for their antigenicity. Four of the 5 affinity purified anti-cardiolipin antibodies had lupus anticoagulant activity providing further evidence to suggest that these 2 groups of antibodies have the same or very similar specificities. Studies of sera from 3 patients with syphilis showed that VDRL liposomes inhibited reagin activity to a greater extent than did cardiolipin. On the other hand, in patients with autoimmune disorders, cardiolipin inhibited anticardiolipin antibody activity to a greater extent than did VDRL liposomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticardiolipin antibodies: occurrence in Behçet's syndrome

Anticardiolipin antibodies have recently been described in association with arterial and venous thrombosis, and with neurological symptoms, in connective tissue diseases. In a study of 70 patients with Behçet's syndrome 13 patients had these antibodies. Of these 13 patients eight had a history of either retinal vascular pathology, cerebral infarction, or thrombophlebitis. The association of retinal vascular disease and the presence of anticardiolipin antibodies was statistically significant.

Inhibitory effect of IgM rheumatoid factor on immune complex solubilization capacity and inhibition of immune precipitation

Purified IgM rheumatoid factors (RF; 3 monoclonal and 2 polyclonal) were shown to inhibit, in a dose-dependent manner, 2 complement-mediated functions, i.e., the immune complex solubilization capacity and the inhibition of immune precipitation. Inhibition of immune complex solubilization capacity occurred only if RF was added at the same time as, but not after, addition of the complement source. Experimental evidence suggests that the effects of RFs were not related to their anticomplementary activity, but rather required the attachment of RF to the Fc region of the IgG molecule. Although no clinical data are available so far, it might be plausible that these newly described properties of RF have biologic relevance.

Solubilization of immune complexes and inhibition of immune precipitation in SLE sera

The ability of serum to in vitro process immune complexes both preformed (ICSC) and during their formation (ICPIC) has been evaluated in 37 patients affected by systemic lupus erythematosus (SLE). ICSC was found to be significantly lower in these patients than in normal controls (p less than 0.001), and strictly related to the phase of the disease. Correlations were evidenced between ICSC and haemolytic activity of the classical and alternative pathways of complement, levels of the complement components C3 and C4, and incidence of circulating immune complexes. Low values of ICPIC were demonstrated almost only in sera of patients with active SLE; in fact, ICPIC was impaired in 6 sera only, and five of them were collected in the acute phase. All sera with decreased ICPIC also displayed a very low level of the C4 complement component.

Con A suppressor cell assay: a further characterization

Con A induced suppressor cell assay was further characterized in this study. Significant lower mitogenic responses of autologous fresh cells cocultured with Con A-activated cells were found when compared with the response of cocultures of responders plus control cells preincubated in medium alone. However, Con A-activated cells did not express a real suppression, since no difference was found between responses of fresh responders alone and responses of cocultures with Con A-activated cells. So, Con A activation seemed to block the expression of the enhancement provided by control cells to autologous responders, rather than to induce a real suppressor activity. The induction of the Con A suppressor cell activity required cell proliferation but it was not proportional to the degree of DNA synthesis. Monocyte depleted cell populations exhibited lower Con A suppressor cell activity compared to unfractionated cells, suggesting a cooperative role of monocytes in the Con A induction step. The expression of this activity was not due to a cytotoxicity against the responders and was dependent on the number of activated cells added. Mononuclear cells from active lupus erythematosus (SLE) patients, but not from inactive SLE patients differed from normal controls in showing a significant loss of suppression index.

Detection of circulating immune complexes in acute non-lymphatic leukaemia: is it reliable?

The in vivo and in vitro phagocytic ability of leukaemic cells and the serum levels of circulating immune complexes (CIC) have been evaluated in 11 patients affected by acute non-lymphatic leukaemia (ANLL). High levels of serum CIC were detected in 17% of the cases showing phagocytic ability and in 80% of the cases lacking phagocytic ability (p less than 0.05). In 3 patients serum CIC determinations were negative while immunoglobulins with complement-fixing ability were detected in the cytoplasm of leukaemic cells indicating in vivo phagocytosis of CIC. These results suggest that leukaemic cells may sometimes interfere through their phagocytic ability on the detection of CIC in the serum. Therefore, the clinical and prognostic value of serum CIC in ANLL seems questionable.

Circulating immune complexes in human acute leukaemia

Circulating immune complexes (CIC) in the sera of 60 newly diagnosed leukaemic patients were investigated by two methods, 125I-C1q binding test (C1q-BA) and conglutinin binding assay (KgB-SP). Positivity percentages were respectively 20.0% (C1q-BA) and 28.3% (KgB-SP). The small overlap between the results of the two methods suggests the occurrence of different types of CIC. The presence of CIC was found to be related only to clinical haemorrhage and thrombocytopenia; it did not prove to affect the prognosis and the survival of leukaemic patient.

Circulating immune complexes in patients with lung neoplasms

A search was made for circulating immune complexes in 42 patients with biopsy-proven lung cancer; sex- and age-matched healthy volunteers were used as normal controls. Two different mthods were employed: Clq--binding assay and the conglutinin-binding test. Patients and controls were also examined for delayed hypersensitivity by a skin testing using a set of recall antigens. A significant difference was found in the incidence of immune complexes and the response to skin tests between neoplastic subjects and normal controls. However, the incidence of immune complexes was not related to delayed hypersensitivity or the other clinical features investigated.

Anti-IgA antibodies in two brothers with selective serum IgA deficiency

A selective serum IgA deficiency with anti-IgA antibodies at high titer were found in a patient who suffered severe transfusion reactions. The same abnormalities were detected in his brother, a 72-year-old-man in good general condition. Anti-IgA antibodies were found in the IgG fraction and were directed against alpha-chains. A deficiency of isoagglutinins and an absence of heteroagglutinins in the propositus' serum could be shown.