EFFECT OF HEAT INACTIVATION AND SHEEP ERYTHROCYTE ADSORPTION ON THE TITER OF ANTICARDIOLIPIN ANTIBODIES IN PRIMARY ANTIPHOSPHOLIPID SYNDROME AND HEALTHY BLOOD-DONORS SERA

The standard enzyme linked immunosorbent assay (ELISA) currently in use for detection of anticardiolipin antibodies (ACA) was used to evaluate the influence of heat inactivation and sheep erythrocyte adsorption on individual optical density (OD) of sera from healthy blood donors or patients with primary antiphospholipid syndrome. Each sample was tested after single or combined maneuvers as follows: adsorbed, adsorbed and inactivated, only inactivated, and compared to basal readings. A significant increase of ACA titers did occur after inactivation of normal sera, but adsorption had no effect. In contrast, neither inactivation nor adsorption changed ACA titer in primary antiphospholipid syndrome sera as a group, although in certain sera there were changes. This observation may suggest the presence in normal serum of a thermolabile factor which modulates ACA binding to its antigen and the reactivity of the anticardiolipin antibodies of the primary antiphospholipid syndrome with sheep erythrocyte membrane phospholipids.