Cardiolipin Antibody (IgM). Cardiolipin antibodies (CA) are seen in a subgroup of patients with autoimmune disorders, particularly systemic lupus erythematosus (SLE), who are at risk for vascular thrombosis, thrombocytopenia, cerebral infarct and/or recurrent spontaneous abortion.linical Significance. Cardiolipin antibodies (CA) are seen in a subgroup of patients with autoimmune disorders, particularly systemic lupus erythematosus (SLE), who are at risk for vascular thrombosis, thrombocytopenia, cerebral infarct and/or recurrent spontaneous abortion.