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Anti-filamentous actin antibodies characterize autoimmune hepatitis type 1 (AIH-1). Recently, the binding domain of alpha-actinin on actin was shown to be a predominant epitope. To test this reactivity, an anti-alpha-actinin enzyme-linked immunosorbent assay was developed, and positivity confirmed by Western blot. Anti-alpha-actinin antibody was found in 21/50 (42%) of AIH-1 patients, compared with 52/401 (12.9%) of liver disease control patients, and with 6/200 (6%) of blood donors. Anti-filamentous and anti-alpha-actinin activities were found specifically together in 66% of anti-filamentous-positive AIH-1 patients. This combination of specificities reflected clinical and histological disease activity, short duration and absence of treatment. Finally, using an actin-alpha-actinin complex assay, the binding of anti-filamentous actin to alpha-actinin-binding domain on actin was demonstrated, as well as that of anti-alpha-actinin on the actin-binding domain of alpha-actinin. Thus, the frequent combination of anti-filamentous and anti-alpha-actinin antibodies seems to be the hallmark of activity in AIH-1.

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To determine whether levels of B cell activating factor (BAFF), a member of the tumor necrosis factor family, relate to autoantibody levels, disease activity, and response to treatment in patients with early rheumatoid arthritis (ERA).BAFF was measured by ELISA in 48 early RA patients; 21 were examined serially. These data were compared with 49 controls with longstanding RA (LSRA), 48 disease controls (DC), and 50 healthy controls (HC).BAFF levels were higher in ERA, compared with DC and HC [median 4.3 ng/ml (5th-95th: 0.8-38.8) vs 0.9 ng/ml (5th-95th: 0.7-4.5) and 2.0 ng/ml (5th-95th: 0.7-5.68), respectively; p10(-4 )both comparisons], but not with LSRA controls [median 8.7 ng/ml (5th-95th: 0.8-46.1); p = nonsignificant]. BAFF correlated with the titers of IgM rheumatoid factor and anti-cyclic citrullinated peptide autoantibody (r = 0.76 and r = 0.49; p0.00001, p = 0.0001 for the 2 correlations), and with the number of swollen joints (r = 0.37; p = 0.01). The followup study of 21 methotrexate-treated ERA patients revealed reduced levels of BAFF, with parallel improvement in clinical activity and decrease in autoantibody titers.Elevated BAFF in a subset of ERA patients is related to autoantibody levels and synovitis. BAFF level diminished with treatment, along with autoantibody titers, suggesting a rationale to treat ERA patients with BAFF-targeted agents.