Sampling duration and anti-C-reactive protein autoantibody (anti-CRP) levels are expressed as a percentage of the positive control on the y-axis. Negative values on the x-axis indicate pre-flare samples, and positive values post-flare samples. Zero on the x-axis marks the time-point of flare. All samples below 0% on the y-axis were considered negative. Six of 10 patients were anti-CRP positive at flare. Patients with active kidney involvement at the present flare are indicated by filled circles, patients without kidney involvement by open circles. Four of four patients with ongoing nephritis were anti-CRP positive at flare.