IgG antibodies to
cardiolipin and
beta 2-glycoprotein I were looked for using an
enzyme-linked
immunosorbent assay (ELISA) in 19 patients with
giant cell arteritis (meeting 1990 American College of Rheumatology criteria), including 16 with concomitant
polymyalgia rheumatica (meeting Bird's criteria) and in three patients with isolated
polymyalgia rheumatica.
IgG anti-
cardiolipin antibodies were demonstrated in eight patients (36%) and
IgG anti-
beta 2-glycoprotein I antibodies in two patients (9%) including one without anti-
cardiolipin antibodies. Titers of anti-
cardiolipin antibodies ranged from 27 to 190 units of
IgG antiphospholipid antibodies (UGPL) (mean 71 UGPL). Of the eight patients with anti-
cardiolipin antibodies, two had
giant cell arteritis without
polymyalgia rheumatica and six had
polymyalgia rheumatica with clinical (n = 2) or histologic (n = 4) evidence of
giant cell arteritis. None of the three patients with
polymyalgia rheumatica but no
giant cell arteritis had anti-
cardiolipin or anti-
beta 2 glycoprotein I antibodies. The VDRL was negative in the 14 patients who had this test. Tests for
lupus anticoagulant were performed routinely, always with negative results. Among
giant cell arteritis patients, those who tested positive for
anticardiolipin antibody had significantly higher values for the erythrocyte sedimentation rate (p < 0.006) and for serum
C-reactive protein (p < 0.03) and
fibrinogen values (p = 0.05), and a trend toward higher platelet counts, as compared to those who tested negative for
anticardiolipin antibody. The mean daily
prednisone dose at the time of sampling was significantly lower in
giant cell arteritis patients with anti-
cardiolipin antibodies (p < 0.05); this difference may account for the apparent correlation between anti-
cardiolipin antibodies and
laboratory markers for
inflammation. These data, as well as findings from serial measurements, suggest that anti-
cardiolipin antibodies are present early in the course of
giant cell arteritis and disappear within a few weeks of initiation of
corticosteroid therapy in a dose of more than 25 mg
prednisone per day. In this study, only one patient without
anticardiolipin antibodies developed a
cerebrovascular accident. Positive tests for anti-
cardiolipin antibody or anti-
beta 2 glycoprotein I antibody in a patient with
polymyalgia rheumatica suggest a diagnosis of concomitant
giant cell arteritis, which is usually symptomatic.