| Description |
The purposes of this thesis were to identify the specific human IgG subclass(es) in patients with lupus anticoagulant (LAC) and antibodies against cardiolipin (CL) and phosphatidylserine (PS); to detect the presence of IgG against other phospholipids such as phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI); and to determine if there was any relationship between the presence of these antibodies and the clinical complications of each patient. IgG against the phospholipids was measured by ELISAs for each phospholipid. IgG subclasses against PS and CL were measured by a solid-phase ELISA using monoclonal mouse antibodies against each human IgG subclass. The sera of 36 patients with lupus anticoagulant and a history of recurrent pregnancy loss were tested. Most patients tested also had one or more of the following clinical complications: antinuclear antibodies, thrombosis, systemic lupus erythematosus, and thrombocytopenia. Controls consisted of sera from 30 antiphospholipid antibody negative women with normal obstetrical and medical histories. All patients had IgG against both PS and CL. Of the other phospholipids tested 97% of the sera had IgG against PI, 91% had IgG against PG, and 82% had IgG antibodies against PE. All patients tested negative for the presence of IgG against PC. IgG2 was the predominant subclass; 35 of 36 patients (98%) had IgG2 against both cardiolipin and phosphatidylserine. Most of the patients also had the IgGl subclass; 32 of 36 (89%) against cardiolipin and 25 of 36 (69%) against phospha-tidylserine. IgG3 subclass was present in 13 of 36 (36%) samples against cardiolipin and in 10 of 36 (30%) samples against phosphatidylserine, and IgG4 subclass was present in 18 of 36 (50%) sera against cardiolipin and in 3 of 36 (8%) sera against phosphatidylserine. When IgG3 and IgG4 subclasses were present, however, they were at very low quantities. It was concluded from this study that: 1) IgG2 is the predominant subclass against CL and PS although IgGl is also commonly present at significant levels, 2) the ELISA's for total IgG against PS and CL correlate very well with the IgG2 subclass but vary in correlation with the other three subclasses, 3) that most of the patients also had IgG against the other phospholipids, possibly cross-reactive in nature, and 4) that there is no association between the presence of a specific subclass of IgG against PS and CL and the presence of IgG against other phospholipids or specific clinical complications. |
