Detection of anti-phospholipid and anti-DNA antibodies and their idiotypes in newborns of mothers with anti-phospholipid syndrome and SLE

The titers, isotypes and idiotypes of antiphospholipid and anti-dsDNA antibodies were determined in seven pairs of mothers with antiphospholipid syndrome (APLS) and their offspring, in 11 pairs of SLE mothers and their matched infants and in seven respective pairs of healthy subjects. In addition, maternal as well as fetal sera were evaluated for the presence of anti-SSA (Ro), anti-SSB (La) and anti-70 kd RNP autoantibodies. In the sera from APLS patients, as well as in the sera from their offspring, the mean antibody titer of IgG aCL was found to be significantly higher then the corresponding value in the control group (P < 0.01). Highly significant increased titers of IgG anti-DNA antibodies were found in the sera of SLE mothers and their matched offspring (P < 0.0008). The prevalence of anti-SSA, anti-SSA, and anti-70Kd RNP antibodies was lower then that of antiphospholipid and anti-dsDNA antibodies. Only one of the respective offspring had increased levels of these antibodies. The quantity of maternal antibodies transferred to the fetus was depended on their concentration in the maternal circulation, as well as on their type and specificity. Follow-up of newborn sera showed a progressive decrease in the antiphospholipid antibody titers during 3 months. After 6 months it was undetected. Our results point to a transplacental transfer of aCL and anti-DNA antibodies, a phenomenon which is not necessarily associated with respective clinical manifestations, in contrast to the classical humoral mediated autoimmune diseases (e.g. myasthenia gravis).

Clinical significance of antineutrophil cytoplasmic autoantibodies with specificity for lactoferrin in renal diseases

The prevalence and clinical significance of antineutrophil cytoplasmic antibodies with specificity for lactoferrin was determined in patients with renal diseases. Antilactoferrin antibodies were found in only 12 of 920 patients (1.3%). These patients had either "pauci-immune" necrotizing crescentic glomerulonephritis (three cases) or lupus nephritis (nine cases). To verify whether antilactoferrin antibodies were specific for patients with systemic lupus erythematosus (SLE) and renal involvement, we studied 61 additional lupus patients, 40 with active lupus nephritis and 21 with active SLE and no renal involvement. Antilactoferrin antibodies were found in approximately 15% to 20% of patients with SLE, irrespective of the presence of renal involvement. We conclude that antineutrophil cytoplasmic antibodies with specificity for lactoferrin are only sporadically found in patients with renal diseases; these patients have either necrotizing crescentic glomerulonephritis or lupus nephritis. However, antilactoferrin antibodies are not a marker for renal involvement in SLE.

Induction of experimental SLE in naive mice by immunization with human polyclonal anti-DNA antibody carrying the 16/6 idiotype

Recently, the induction of SLE in naive mice employing monoclonal anti-DNA antibodies (anti-DNA Ab) carrying the pathogenic idiotype 16/6 (16/6 Id) has been reported. In the current study we report on the induction of experimental SLE by polyclonal IgG anti-DNA Ab derived from a patient with active SLE and carrying the 16/6 Id. Two different experiments were conducted in which BALB/c mice were immunized in the footpads with 1 microgram/ml or 5 micrograms/ml of anti-DNA Ab. The first experiment showed the appearance in the immunized mice of high titre anti-DNA Ab together with antinuclear antibodies, alopecia and proteinuria. In the second experiment we compared, as immunizing agents, 16/6 positive anti-DNA Ab and 16/6 negative anti-tetanus toxoid antibodies (anti-TT Ab) obtained from the serum of the same patients. Our results show that only mice immunized with 16/6 positive antibodies produced anti-DNA Ab, while mice immunized with anti-TT Ab did not show any DNA-binding activity but, surprisingly, developed high titre anti-cardiolipin antibodies.

ANCA with specificity for lactoferrin in systemic lupus erythematosus (SLE)

Antibodies to lactoferrin were detected in about 20% of patients with SLE, irrespective of the presence of renal involvement and in 10% of patients with rheumatoid arthritis and in 19% of patients with scleroderma. We conclude that anti-lactoferrin antibodies may be found in different types of connective tissue disease. Their clinical significance in these diseases however remains to be elucidated.

Systemic lupus erythematosus and pregnancy: a prospective study

We have prospectively followed 25 pregnancies in 21 patients: 20 were affected by systemic lupus erythematosus (SLE) and 1 by subacute cutaneous lupus erythematosus (SCLE). A flexible treatment schedule was applied to the follow-up of all the pregnancies, and included low dose aspirin, steroids at medium-low dosage and, if needed, azathioprine (AZA) after 20 weeks of gestation. There were 4 spontaneous first trimester abortions and 21 live-born neonates without major problems related to the treatment or to the maternal disease. The relapse rate of the disease recorded during the observation period was 0.07 patient/month, not different from that already reported in SLE patients (pregnant or nonpregnant). Obstetrical complications were relatively frequent, but careful monitoring allowed us to avoid late fetal wastage. We conclude that in SLE patients a successful pregnancy outcome, without worsening of the disease, can be obtained with a careful multidisciplinary follow-up.

Antiphospholipid antibodies cross-reacting with erythrocyte membranes. A case report

We describe a patient with primary antiphospholipid syndrome (PAPS) and haemolytic anemia with cryoagglutinins, in whom antibodies eluted from red blood cells (RBC) displayed anti-cardiolipin (CL) binding activity. This activity was confined to the IgG isotype and was directed to the negatively-charged phospholipids only. In addition, the patient's IgG fraction displayed a higher binding to RBC in comparison to normal control IgG and this reactivity was inhibited after absorption of the anti-CL activity with CL-micelles. These findings further sustain the association between antiphospholipid antibodies (APA) and Coombs' positivity with or without haemolytic anemia and suggest that APA could be at least in part responsible for anti-RBC activity.

Antibodies to endothelial cells in primary vasculitides mediate in vitro endothelial cytotoxicity in the presence of normal peripheral blood mononuclear cells

Twenty-eight out of 62 patients with Wegener's granulomatosis and micropolyarteritis display circulating antiendothelial cell antibodies (AECA) detectable by a cell surface radioimmunoassay. These antibodies do not induce an in vitro endothelial damage either alone or in the presence of fresh complement; however, 50% of IgG-AECA positive sera can be cytotoxic in the presence of human normal peripheral blood mononuclear cells (PBM) at high effector/target ratios. The specificity of the PBM-mediated cytotoxicity is supported by the absence of the phenomenon in AECA negative sera, by the disappearance of the lytic effect after absorption of AECA, and by the finding that cellular-mediated cytotoxicity can be reproduced by purified IgG-AECA positive fractions. On the contrary, polymorphonuclear leukocytes or adherent mononuclear cells are not involved in such a cytotoxic activity. AECA seem to be directed against determinants consitutively expressed on the endothelial surface since the activation of endothelial cells by interleukin-1 beta or interferon-gamma affects neither the antibody binding nor their ability to mediate 51Cr release in the presence of PBM. These findings favor the hypothesis for a possible direct pathogenetic role of circulating AECA in the in vivo vascular damage.

Relationship between anti-phospholipid and anti-endothelial cell antibodies: further characterization of the reactivity on resting and cytokine-activated endothelial cells

Sera positive for autoimmune anti-phospholipid antibodies were studied by a cell surface radioimmunoassay for their cross-reactivity with resting or activated human endothelial cells. The endothelial cell activation by interleukin 1 beta, gamma-interferon, lipopolysaccharide or phorbol-12 myristate-13 acetate did not affect the cross-reactivity. Comparable findings were also found by testing anti-cardiolipin affinity purified preparations. Taken together these data indicate that endothelial cell activation is not sufficient per se to modulate the expression of antigenic determinants recognizable by the anti-phospholipid antibodies. However, anti-cardiolipin affinity purified preparations displayed enhanced cell binding after cell membrane perturbation by paraformaldehyde fixation, suggesting that an alteration in endothelial cell integrity might further trigger the reaction of circulating anti-phospholipid antibodies with vessel walls in vivo.

Decreased number of peripheral blood CD4 + CD29+ lymphocytes and increased in vitro spontaneous production of anti-DNA antibodies in patients with active systemic lupus erythematosus

Flow cytometric 2-color analysis of peripheral blood lymphocytes from patients with systemic lupus erythematosus (SLE) showed a reduction of relative and absolute number of CD4+ CD29+ cells compared to matched healthy individuals. This abnormality was more marked in patients with active/very active disease. Absolute number of CD4+ CD29+ cells was negatively correlated with spontaneous anti-DNA Ig production that we demonstrated to be a laboratory index strongly correlated with a clinical disease activity score. A decrease of the percentage of CD8+ CD29+ lymphocytes in patients with active disease was also observed.

Anti-endothelial cell antibodies in patients with Wegener's granulomatosis and micropolyarteritis

Anti-endothelial cell antibodies (AECA) have been detected by cell surface radioimmunoassay in nine out of 15 patients with micropolyarteritis (MPA) and in two out of five patients with Wegener's granulomatosis. AECA mostly belonged to the IgG isotype and were present in the active phase of the diseases. These antibodies were not detectable in 10 sera from patients with essential mixed cryoglobulinaemia, suggesting that they were not a mere epiphenomenon consequent to the inflammatory vascular injury. The binding activity was not related to ABH antigens or to HLA class I antigens displayed by resting human endothelial cells in culture and was not influenced by removing immune complexes. Absorption of the anti-neutrophil cytoplasmic antibodies (ANCA), present in MPA and Wegener's granulomatosis sera, did not affect the endothelial binding. AECA-positive sera did not display lytic activity against endothelial cells, neither alone nor after addition of fresh complement or normal human peripheral blood mononuclear cells. Although AECA are not cytolytic for endothelial cell monolayers in vitro, the reactivity against intact endothelial cells suggests their possible involvement in in vivo pathological processes affecting vascular structures in small vessel primary vasculitides.

Anticardiolipin antibodies possess anticoagulant activity which is blocked by a monoclonal antibody against a cross reacting idiotype of antiphospholipid antibodies

Anticardiolipin (aCL) antibodies were isolated from systemic lupus erythematosus serum using cardiolipin liposomes. In a sensitized activated partial thromboplastin time (aPTT) system, low concentrations of aCL were found to significantly prolong aPTT in a dose-dependent fashion. This effect was abolished by adding phosphatidylserine/phosphatidylcholine liposomes to the aPTT system, and could be significantly reduced by a monoclonal antibody against a cross-reacting idiotype of antiphospholipid antibodies (MoAb 5.2) previously incubated with aCL. These results suggest that the anticoagulant properties of aCL are mediated by an interaction with phospholipid components of the coagulation system. The functional block of this activity using monoclonal MoAb 5.2 antibody could be useful for investigating the mechanisms by which aCL is associated with clinical thrombosis.

The pathophysiology of anti-phospholipid antibodies

Anti-phospholipids represent a heterogeneous family of antibodies able to react with the negatively charged phosphodiester groups of phospholipids. It includes the antibodies directed against the cardiolipin moiety of the VDRL antigen, the antibodies reacting with the phospholipids of the prothrombin activator complex and the antibodies able to react with solid phase cardiolipin. Data are reported indicating that reagins share distinct characteristics in comparison to the autoimmune anti-cardiolipin antibodies (ACA). On the contrary anti-phospholipid antibodies responsible for lupus-like anticoagulant activity display a quite similar reactivity with ACA, even if a complete overlapping cannot be demonstrated. The relationships between ACA and anti-DNA antibodies are also reported. The biological and clinical significance of these crossreactivities are discussed.

HLA-DR antigens and anticardiolipin antibodies in northern Italian systemic lupus erythematosus patients

Eighty systemic lupus erythematosus (SLE) patients attending 3 clinical centers were evaluated immunologically and immunogenetically. No HLA class II antigens were found to be significantly associated with SLE in these patients. A highly significant (P = 6.17 x 10(-7) association was observed between anticardiolipin antibodies and DR7. A lesser association (P less than 0.025) was also observed between DR2 and/or DR3 and anti-Ro (SS-A) antibodies. No relationship was found between any DR antigen and anti-Sm/RNP, anti-double-stranded DNA, or anti-La (SS-B) antibodies.

Relationship between anti-cardiolipin and anti-endothelial cell antibodies in systemic lupus erythematosus

Anti-endothelial cell antibodies (AECA) have been detected in 51 lupus sera by cell surface radioimmunoassay with a prevalence of 39.2% for IgG and 45.1% for IgM-AECA. No correlations were found between AECA and different clinical or laboratory parameters, including the presence of anti-cardiolipin antibodies and signs associated with the presence of anti-phospholipid antibodies. However, absorption with cardiolipin liposomes partially inhibited endothelial cell binding, and affinity purified anti-cardiolipin antibodies were able to react with intact human endothelial cells. The binding did not occur via Fc receptors since blocking of Fc receptors with rabbit IgG did not affect the endothelial cell reactivity. Taken together our findings support the hypothesis that antibodies directed against negatively charged phospholipids can be part of the anti-endothelial cell antibodies in certain lupus sera. The possible role of these cross-reacting antibodies in the pathogenesis of vascular thrombosis in lupus patients is discussed.

Autoantibodies and common idiotypes in men and women with sperm antibodies

Antisperm antibodies have been implicated as a causative factor of infertility and pregnancy wastage. Since concomitant autoimmune phenomena were reported in men with antisperm antibodies, we investigated known antisperm antibody-positive sera from 25 women, 27 men, and the respective seminal plasma samples. The investigated autoimmune panel included a search for antinuclear antibodies, autoantibodies (in IgG, IgM and IgA isotypes) to seven phospholipids (cardiolipin, phosphatidylserine, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid), to four histone subfractions (H1, H2A, H3, H4), and to four polynucleotides [ssDNA, dsDNA, poly(I), and poly(dT)], total immunoglobulin levels, and sperm antibody titers. The sera were also evaluated for the presence of a common anti-deoxyribonucleic acid antibody, and anticardiolipin antibody idiotypes. Levels of sperm antibody titers were significantly lower in women than in men. Both men and women with antisperm antibodies demonstrated elevated total IgG levels compared with those of normal control subjects. Only women showed elevated levels of total IgM. Sera from 24% of women and 11% of men with antisperm antibodies demonstrated antinuclear antibody titers greater than 1:40. The most striking autoantibody abnormalities were found among antiphospholipid antibodies. Sera from women with antisperm antibodies demonstrated higher autoantibody production than was found in their male counterparts. A significant correlation was found between antisperm antibodies and IgM anticardiolipin and IgA anti-phosphatidylinositol in women and between sperm antibodies and IgA phosphatidylserine antibodies in men. The presence of anticardiolipin and anti-deoxyribonucleic acid antibody idiotypes was significantly more frequent in women than in men. By means of discriminant analysis and variables selected by this mathematical model, the identification of 24 of 25 women and 26 of 27 men with antisperm antibodies was correctly predicted. These results suggest that women and men respond differently to sperm antigens. The apparent cross-reactivity between sperm antibodies and other autoantibodies, usually associated with autoimmune disease, suggests that a polyclonal B cell activation, similar to that seen in autoimmune diseases, occurs in patients with sperm antibodies.

Use of monoclonal antibodies to identify shared idiotypes on anticardiolipin and anti-DNA antibodies in human sera

Using hybridoma technology we produced monoclonal antibodies (MoAb) to idiotypic determinants on human anti-cardiolipin antibodies purified from a patient with SLE. Hybridomas were screened by inhibition of cardiolipin binding activity of sera from patients with SLE. Seven hybridomas were selected, two of which were studied extensively. Sera from a number of patients with SLE were found to share idiotypic determinants. This cross-reacting idiotype was not detectable on anti-cardiolipin antibodies in syphilis sera. The cross-reacting idiotype was present in sera with anti-ssDNA antibodies even though some of these sera had no anti-cardiolipin antibodies. We propose that these MoAb may recognize a regulatory idiotype.

Anti-mitochondrial type M5 and anti-cardiolipin antibodies in autoimmune disorders: studies on their association and cross-reactivity

In a series of 42 positive sera, anti-mitochondrial type M5 antibodies (AMA-M5) were found most frequently in patients with SLE (24) and SLE-like syndromes. Patients with AMA-M5 displayed a higher prevalence of thrombocytopenia, thrombosis, biological false positive seroreactions for syphilis, lupus-like anticoagulant activity and anti-cardiolipin antibodies in comparison with a group of 43 SLE AMA-M5 negative patients. The strong association between anti-phospholipid and AMA-M5 antibodies cannot be explained entirely by cross-reactivity between these two groups of antibodies, as indicated by absorption experiments and studies using affinity purified antibody preparations. However, cardiolipin liposomes were able to reduce partially the titres of AMA-M5 sera, suggesting that a small population of AMA-M5 antibodies exists that cross-reacts with cardiolipin. The existence of this population was further substantiated by our demonstration that an IgM monoclonal antibody, from a patient with Waldenström's macroglobulinaemia, displayed both anti-cardiolipin and AMA-M5 activity, and AMA-M5 activity was completely inhibited by cardiolipin.