Depletion of Vbeta5.2/5.3 T cells with a humanized antibody in patients with multiple sclerosis.

A potentially pathogenic expansion of T cells expressing T cell receptor (TCR) Vbeta5.2/5.3 has been demonstrated in patients with multiple sclerosis (MS). A humanized antibody (ATM-027) directed against these T cells has been developed to further investigate the role of this subpopulation of T cells in MS. The pharmacokinetics/dynamics and safety of ATM-027 (0.3-300 mg intravenously over 30 min) were investigated in 14 patients with MS. The effect of treatment on cytokine expression and autoreactivity to peptides of myelin basic protein (MBP) was also studied. ATM-027 was well tolerated and raised no safety concerns. Clearance of the antibody was low and elimination half-life was approximately 3 weeks. The majority of the target Vbeta5.2/5.3 expressing T cells were depleted for at least 18 months. The small remaining fraction of target cells showed a marked decrease in their TCR expression, which was recovered within 8 months. The numbers of peripheral blood mononuclear cells (PBMCs) with spontaneous expression of IFN-gamma was decreased at 72 h and 8 weeks after treatment, whilst no clear effects on TNF-alpha, IL-4, IL-10, TGF-beta expression were observed. There was also a significant decrease in the number of PBMCs producing IFN-gamma in response to MBP peptide 80-102. We conclude that long-term depletion of T cells expressing defined Vbeta subgroups in MS patients is feasible using selective immunotherapy. The selective depletion of Vbeta5.2/5.3 expressing T cells in this study resulted in a decrease in potentially disease promoting anti-MBP reactivity and pro-inflammatory cytokine production.

Enrichment of antibodies against phospholipids in circulating immune complexes (CIC) in the anti-phospholipid syndrome (APLS).

The aim of this study was to analyse and characterize immunoglobulins in CIC and serum from patients with anti-cardiolipin antibodies. CIC from five patients were isolated by gradient centrifugation and gel filtration. The distribution between serum and CIC of immunoglobulin reactivity against different phospholipids was determined. Serum and CIC contained antibodies against cardiolipin and other negatively charged phospholipids. The relative concentration of these antibodies was higher in the immune complexes than in corresponding sera, and the avidity of antibodies in immune complex form was higher. The presence of high concentrations of antibodies to negatively charged phospholipids in CIC from patients with anti-cardiolipin antibodies could be of pathogenic significance in APLS by conferring characteristics to the complexes of importance for binding to membrane components. This could have special implications with regard to platelet and complement activation, thrombocytopenia and thrombophilia.

Prevalence of antibodies to cardiolipin in chronic ITP and reactivity with platelet membranes.

UNLABELLED: Anti-cardiolipin antibodies (ACLA) have been suggested to play a role in the pathogenesis of thrombocytopenia. When sera from 40 patients with chronic idiopathic thrombocytopenic purpura (ITP) were analyzed for ACLA, these autoantibodies were present in 12 (30%). In 4 sera the antibody activity was restricted to the IgG or IgM isotype, respectively, while 4 of the samples contained both IgG and IgM antibodies. To elucidate the interaction between platelets and ACLA, we studied the reactivity of sera from non-ITP patients with ACLA, with fragmented platelet membranes. None of them had a concurrent platelet deficiency, but sera from 8 (67%) of them showed increased IgG-binding to platelet membranes. Absorbtion with cardiolipin reduced membrane binding in 6 (50%). C3 levels were normal, while low C4 values occurred in both groups with significantly lower levels in ACLA-positive patients (p<0.05). Circulating immune complexes (CIC) were common in both groups. CONCLUSION: The prevalence of ACLA is increased in ITP and sera from non-ITP patients with ACLA react with fragmented platelet membranes. This reactivity is often decreased by absorption with cardiolipin, suggesting that ACLA bind to phospholipid epitopes on platelet membranes.

Opinions on treatment of women with habitual abortion based on investigations for blocking antibody and autoantibodies.

Three hundred and thirty-seven women with habitual abortion of unknown etiology were studied for cellular reactivity and blocking antibody in one-way mixed lymphocyte culture. Their sera were investigated for anti-cardiolipin antibodies, antinuclear antibodies, and antibodies against DNA, and the activated partial thromboplastin time (APTT) and complement levels of their plasma were determined. Increased anti-cardiolipin antibody levels were demonstrated in 77 (22%) of the 337 women, all of whom were considered healthy and had no signs of autoimmune disease. Most patients with high anti-cardiolipin antibody levels displayed lowered values of complement factor C4. According to our experiences, the mere occurrence of anti-cardiolipin antibody in women with habitual abortion is no absolute cause for treatment with prednisolone, not even in cases with greatly elevated anti-cardiolipin values. Therapy with prednisolone and acethylsalicylic acid (ASA) during pregnancy should be given to those women who have high levels of anti-cardiolipin antibodies concomitant with high APTT values, low values of complement C4, and strong blocking antibody. Anti-cardiolipin antibody has been investigated during pregnancy in 136 normal pregnant women, 11 of whom (8%) were positive at any sampling occasion, but only one of whom (1%) had high levels. Evidently the development of anti-cardiolipin antibody is no normal feature of pregnancy among Swedish women and thus the high frequency found among healthy Swedish women with habitual abortion remains unexplained. We have introduced an immunization program of leukocyte transfusions in habitual abortion. The development of previously absent blocking antibody seems to be a valuable prognostic sign of possible success for immunization therapy against habitual abortion.

Increased thromboxane formation in patients with antiphospholipid syndrome.

Thirty-one patients with IgG antibodies to cardiolipin (ACLA) were studied to determine their in vivo formation of the platelet aggregating and vasoconstricting substance thromboxane A2 (TxA2) and the platelet inhibiting and vasodilating substance prostacyclin (PGI2). This was done by measurements in urine of their enzymatically formed metabolites 2,3-dinor-TxB2 and 2,3-dinor-6-keto-PGF1 alpha, respectively, using gas chromatography-mass spectrometry. It is demonstrated that patients with IgG ACLA have a highly significant increase in the biosynthesis of TxA2 compared with age-matched healthy controls (807 +/- 163 [SEM] vs. 230 +/- 15 pg mg-1 creatinine, P = 0.0000005). A significant increment of the formation of PGI2 was also found (189 +/- 23 (SEM) vs. 125 +/- 11 pg mg-1 creatinine, P = 0.03), although this was much less pronounced than that for TxA2. We conclude that the highly increased formation of TxA2, reflecting platelet activation, in patients with IgG ACLA is of pathophysiologic relevance for their tendency to arterial and venous thrombosis and hence that they should be considered for prophylactic treatment with inhibitors of TxA2 formation, like aspirin.

Pemphigoid and cancer.

To evaluate the significance of the association of malignant disease with bullous pemphigoid, we reviewed 497 consecutive cases with positive immunofluorescence tests for circulating antibodies to basement membrane. We searched the Swedish Cancer Registry, Stockholm, Sweden, for records reporting malignancies in the study population (1958 to 1985), and the expected number of malignancies was calculated on the basis of age- and sex-standardized incidence data. In 61 patients, a total of 69 malignancies were diagnosed. The expected number of malignancies was 82.6. In 25 patients, a total of 27 malignancies appeared during the same year as the onset of pemphigoid, or later. The expected number was 35.8. The median titer of circulating antibodies in the 497 patients, in the 61 patients with malignancy, and in the 25 patients with malignancy preceded by the pemphigoid, were not significantly different. We conclude that pemphigoid is not statistically associated with malignancy, and that the former hypothesis of such an association was based on age only.

The results of investigations for blocking antibody and autoantibodies help to choose between different immunological treatments for recurrent abortion.

Immunologic investigations were performed on 337 healthy women with unexplained habitual abortion. Their sera were investigated for antinuclear antibodies (ANA), antibodies against DNA, and anti-cardiolipin antibodies, and the activated partial thromboplastin time (APTT) and complement levels of their plasma were determined. Cellular reactivity and blocking antibody were studied in one-way mixed lymphocyte culture (MLC). None of the women had any signs of autoimmune disease. However, in 77 of the 337 women (22%) increased anti-cardiolipin antibody levels were found, in 19 (7%) above 10 units. Most patients with high anti-cardiolipin antibody levels had lowered values of complement factor C4. We consider the mere occurrence of anti-cardiolipin antibody in women with habitual abortion to be no absolute cause for treatment with prednisolone, and this is true even in cases with very elevated anti-cardiolipin values. Treatment with prednisolone and acetylsalicylic acid (ASA) during pregnancy should be given to only those women who have high levels of anti-cardiolipin antibodies concomitant with high APTT values, and low values of complement C4. Anti-cardiolipin antibody was also investigated during pregnancy in 136 normal pregnant women. Eleven of them (8%) were positive at any of four sampling occasions, but only one (1%) had high levels. These data differ significantly from those of the habitual aborters. Thus the development of anti-cardiolipin antibody is no normal feature of pregnancy in Swedish women and so the high frequency found among healthy Swedish women with habitual abortion remains unexplained. We have introduced an immunization programme of third party leukocyte transfusions in habitual abortion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticardiolipin and complement activation: relation to clinical symptoms.

Anticardiolipin antibodies which seldom occur in healthy persons are frequently found in systemic lupus erythematosus (SLE). Their presence, especially at high levels (greater than 10 units) are often accompanied by thromboembolic manifestations as well as thrombocytopenia and recurrent abortions. The incidence of cardiolipin antibodies was as great in SLE as in women with clinically unexplained recurrent abortions. The anticardiolipin levels remained unchanged in most patients for long periods and were remarkably unaffected by disease activity and therapy. On the other hand, in several cases the activated partial thromboplastin time which was prolonged in most patients with persistently high cardiolipin antibody levels, approached normal during treatment with prednisolone and salicylic acid. This seemed to facilitate a successful outcome of pregnancy. Absorption of sera with cardiolipin and other negatively charged phospholipids but not with uncharged phospholipids abolished the anticardiolipin activity in enzyme linked immunosorbent assay. In most sera with cardiolipin antibody levels greater than 10 units complement activation by the classical pathway could be demonstrated. Whether the anticardiolipin antibodies contributed to complement activation could not be determined.

Anticardiolipin antibodies and complement in ninety-nine women with habitual abortion.

Immunologic investigations were performed on sera from 99 women with habitual abortion (three or more consecutive miscarriages). All were considered healthy and clinical investigations had not revealed any cause for the miscarriages. Sixty-eight were considered to have primary habitual abortion whereas 31 had secondary habitual abortion. Increased anticardiolipin antibody levels were found in 42 patients. None had a primary diagnosis of systemic lupus erythematosus, but at follow-up studies one of them fulfilled the diagnostic criteria of systemic lupus erythematosus. Ten sera, all from patients with primary habitual abortion, showed high anticardiolipin antibody values (greater than or equal to 10 units) concomitant with significantly lower levels of complement factor C4 than those found in sera with moderate or normal anticardiolipin antibody levels. There was no indication of genetic defects explaining the low C4 values, which could be explained at least in part by an activation of complement by the classical pathway.