Las controversias respecto al diagnóstico y tratamiento del TDAH

The term “Lupus” means wolf in Latin and was used by a 13‘*^ century physician called Rogerius to describe erosive facial lesions that were reminiscent of a wolfs bite (Blotzer 1983). It was only in 1851 that the Frenchman Cazenave applied the term “lupus erythematosus” as described by his teacher Laurent Biett (Talbot 1974). In 1872, Moretz Kaposi recognized visceral involvement of lupus and proposed two types of disease, the discoid and disseminated forms. By the 1920s and 1930s SLE had been widely accepted as a distinct clinical entity. The renal “wire loop” lesion findings were first described by George Baeher (Lahita 1999a). In 1936, Friedberg, Gross and Wallache made a post mortem diagnosis of SLE with no cutaneous lesions proving for the first time that the disease could occur without skin manifestations (Lahita 1999a). A false positive syphilis test was reported in 10 patients with SLE by Keil in 1940. The discovery of the LE cells by Hargraves in 1948 and the development of the LE cell test facilitated the ability to diagnose SLE. The serum component responsible for LE cell formation was shown to be gammaglobulin which reacted with intact nuclei and nucleoproteins (Holman et al 1957). Schett et al (2000) have compared and investigated anti-histone and anti-chromatin antibody responses as well as clinical variables in patients with systemic lupus erythematosus (SLE) who were either LE cell positive (LEC+) or LE cell negative(LEC-). The anti-histone HI reactivity was found to be 8 fold higher in LEC+ sera than in LEG- sera. Reactivities to most of the other antigens such as other histones, histone-DNA complexes, DNA and chromatin were also found to be higher in LEC+ sera than in LEG- sera. Thus a positive LE cell phenomenon correlated with presence of

high anti-histone HI antibody levels in SLE and with clinically active disease with major organ involvement.

The fluorescent antibody method discovered by Coons et al in 1941 employed immune serum globulin labelled with a fluorescent dye to locate the corresponding antigen. The conjugation method was later modified using fluorescein isothiocyanate (FITC) and was introduced by Riggs et al (1958).

Anti-nuclear antibody or anti-nuclear factor is a highly sensitive marker for SLE and occurs in >95% of SLE patients with disease. Anti-nuclear factor or anti- nuclear antibody (ANA) was first demonstrated in the sera of SLE patients using immunofluorescent techniques by Friou et al (1957) and Holborow et al (1957). Some other tests have also been used for the detection of ANA, such as the anti-globulin consumption test, complement fixation test, double gel diffusion test (Ouchterlony), electroimmunodiffusion test, agglutination test, radioimmunoassay (RIA) and enzyme linked immunosorbent assay (ELISA) (Morrow et al 1999a). Anti- nuclear factors were not found to be species-specific and therefore nuclear material from a wide variety of human and animal sources could be used for staining.

Lupus or systemic lupus erythematosus (SLE) is considered a classical autoimmune disease that involves many organs or systems. A significant feature of SLE is the presence of diverse and heterogenous autoantibodies against a variety of body constituents like DNA, erythrocytes, leucocytes, platelets, cell nuclei, ribonucleoproteins, histones, soluble nuclear glycoproteins, cytoplasmic antigens and nucleosides. Anti-dsDNA antibodies are considered the immunologic hallmark and diagnostic marker of SLE . Anti-dsDNA antibodies

are found in about 70% of SLE patients’ sera at some point during their disease and are 95% specific for the diagnosis of SLE and are known to contribute to the disease pathogenesis of SLE (Weinstein et al 1983). Anti-dsDNA antibodies have been discussed in detail later on in this thesis. Autoantigens reacting with SLE autoantibodies are frequently coupled as supramolecular complexes such as RNA-protein (RNP, spliceosomes), DNA-protein (DNP, nucleosome), and protein-protein (SSA/Ro subunits) (Hardin et al 1986, Reichlin 1994). Antibodies to extractable nuclear antigens which are conventionally divided into Ro (SS-A), La (SS-B), Sm (Smith antigen) and RNP (ribonucleoprotein) are of relevance as useful clinical markers. Both Sm and nRNP (nuclear ribonucleoprotein) belong to the group of small nuclear ribonucleoproteins (snRNPs) which are complexes of small nuclear RNAs with proteins and both are active components of the spliceosome (Luhrman et al 1990). Anti-Sm antibodies are produced by approximately 25% of lupus patients and is considered a highly specific disease marker for SLE (Tan et al 1982). It has not been detected in normal sera or in patients with other systemic rheumatic diseases such as Sjogren’s syndrome, mixed connective tissue disease (MCTD), scleroderma, polymyositis or drug induced lupus erythematosus (Notman et al 1975, Tan 1989). Anti-Sm antibodies do not have a strong association with any particular disease feature. Over 80% of sera positive for Sm (virtually always from patients with SLE) also contain antibodies to nRNP. Anti-nRNP antibodies are found in about 40% of SLE patients and are not associated with any particular disease features in lupus. Anti- nRNP antibodies have also been found to occur in patients with undifferentiated rheumatic disease (UARD) in high titers (Morrow et al 1999b). Antibodies to Ro

and La are both associated with neonatal lupus syndrome . Antibodies to La are particularly associated with the coincidence of Sjogren’s syndrome and lupus and are known to occur in 15-20% of SLE and 45-60% of Sjogren’s syndrome patients. Antibodies to Ro occur in 60-70% of patients with Sjogren’s syndrome and 40% of patients with SLE (Chan et al 1992, von Muhlen et al 1995). Patients with anti-La antibodies are less likely to have renal disease (Maddison et al

1988). Anti-Ro antibodies are associated with photosensitive rashes, the so called subacute cutaneous form of lupus and vasculitis. Immune complexes containing Ro may participate occasionally in renal inflammation, as increased Ro activity has been found in glomerular eluates in the kidneys of two patients who died with severe lupus nephritis (Maddison and Reichlin 1979).

Anti-phospholipid antibodies (aPLs) are present in a wide range of infectious and autoimmune diseases. APLs, in particular anti-cardiolipin antibodies (aCLs) and lupus anticoagulants (LAs), are of considerable importance because of the close association with predominant clinical features of venous and arterial thrombosis, recurrent pregnancy loss and thrombocytopenia (Harris et al 1985, Triplett et al 1994). The term ‘anti-phospholipid syndrome (APS)’ has been used to define this term. LAs are defined as immunoglobulins (IgG, IgM, IgA or their combination) that interfere with in vitro phospholipid dependant tests of coagulation. The lupus anticoagulants were so called since they were originally detected in the plasma of patients with SLE but this term is a misnomer since many patients with LA do not have SLE. Anti-cardiolipin antibodies are present in 20-50% of lupus patients and lupus anticoagulants in 15-35% (Isenberg and Horsfall 1998). Anti-cardiolipin antibodies have also been detected in patients

with other autoimmune disorders such as connective tissue diseases, vasculitic disorders, diabetes mellitus, patients with infectious diseases and patients with malignancies. P2 glycoprotein-I also known as apolipoprotein H, is a plasma protein with an in vitro anti-coagulant activity and has been characterized as an antigenic target for anti-phospholipid antibodies (Matsuura et al 1994, Roubey et al 1995). The association of anti-^2 glycoprotein-I with the clinical manifestations of the anti-phospholipid syndrome in patients with SLE has been found to be stronger than anti-cardiolipin (Cabiedes et al 1995). The APS that can be found in patients having neither clinical nor laboratory evidence of another definable condition is classified as primary APS whereas APS associated with other diseases is classified as secondary APS.

In one of the studies conducted in this thesis, I have addressed the possibility that protein antigens may act as triggering antigens in the anti-DNA response. I studied the potential of peptides (notably the R4A peptide) derived from screening a phage display peptide library with the R4A antibody, which is a murine pathogenic anti-DNA antibody, to inhibit the binding of anti-dsDNA and anti-cardiolipin to dsDNA and cardiolipin respectively. Anti-cardiolipin antibodies were included in this study since previous murine studies by Putterman et al (2000) have demonstrated that both anti-DNA and anti- cardiolipin antibodies crossreact with the R4A peptide. Studies by Diamond and Scharff (1984) showed that a single mutation of alanine to glutamic acid at position 35 on the heavy chain of a murine anti-PC antibody resulted in loss of specificity for phosphorylcholine. This antibody however gained specificity for

dsDNA and cardiolipin which suggests the significance of a link between anti- DNA and anti-cardiolipin antibodies.

Similar to other autoimmune conditions, the aetiology of SLE is multifactorial entailing genetic, environmental, hormonal and immunologic factors.