| • | antiphospholipid antibodies are the cause for the biologic false-positive serologic tests for syphilis |
| • | antiphospholipid antibodies are generally divided into two groups (some sera may be positive by one assay and negative by the other) on the basis of the laboratory methods used to identify them: |
1 - ELISA using bovine cardiolipin:
| • | the term anti-cardiolipin antibodies is frequently used interchangeably with APA’s antiphospholipid antibodies |
| • | because of the high degree of sensitivity, ELISA is recommended as the screening test for APA |
| • | if the ELISA is negative in a patient highly suspected of having APA, the lupus anticoagulant assay may be obtained |
2 - lupus anticoagulant assay:
| • | I think that this is essentially an increased PTT that does not correct when adding back clotting factors but does correct when adding back phospholipid |
ANTIPHOSPHOLIPID ANTIBODIES:
| • | APA’s are most prevalent in patients with SLE (~50%) |
| • | reagin – the first antiphospholipid antibody discovered; made in response to infection with syphilis; detected using cardiolipin |
| • | lupus anti-coagulant – blocks the interaction of the phospholipid dependent coagulation factors with each other and calcium in vitro |
| • | paradoxically associated with both venous and arterial thrombosis |
| • | causes increased PTT, thrombocytopenia, and biologic false positive serologic tests for syphilis |
| • | anti-cardiolipin antibodies - the term is frequently used interchangeably with APA’s |
PHOSPHOLIPIDS:
| • | cardiolipin – a phospholipid plentiful in beef heart; used to detect reagin |
| • | phosphatidyl serine, phosphatidyl choline |
clinical (patients with antiphospholipid antibodies may have one or more of the following, or even no disease symptoms at all):
| • | recurrent DVT; arterial thrombosis |
| • | recurrent spontaneous abortion |
| • | thrombocytopenia --> petechiae |
| • | cutaneous (25%): digital gangrene +/- Raynaud’s, livedo reticularis, purpura, necrosis, or ulcers |
histology:
| • | thrombosis without vasculitis |
syndromes in which APL’s may play a role (in at least some cases): Sneddon syndrome, Degos disease
|