Epidermal in vivo nuclear staining is occasionally noted in the lupus band test (LBT) in patients with connective tissue diseases (CTD). The exact clinical significance of this finding remains unelucidated, especially in association with a positive LBT We have reviewed the clinical and serological characteristics of patients with in vivo-bound antinuclear antibodies (ANA) in keratinocytes.
Between 1990-1999 speckled IgG staining in keratinocyte nuclei was observed in 31 LBT specimens. We had detailed clinical and laboratory data for 22/31 patients. The present study comprises 22 patients with in vivo-bound ANA (8 cases with mixed CTD (MCTD), 10 with systemic lupus erythematosus (SLE), 2 with Sjögren's syndrome (SS), one with undefined CTD and one clinically healthy mother of a child with neonatal lupus erythematosus), and 22 consecutive CTD patients (2 MCTD, 15 SLE, 5 SS) without in vivo-bound ANA. Antinuclear, anti-dsDNA and anti-extractable nuclear antigens (ENA) antibodies were determined using indirect immunofluorescence and ELISA methods.
A significant difference (p < 0.01) in anti-RNP antibodies between patients with and without in vivo-bound ANA was observed. Consequently, there was a strong association of in vivo-bound ANA and anti-RNP antibodies (p < 0.01). In SLE patients with in vivo-bound ANA the incidence of nephropathy was significantly lower (p < 0.01), regardless of LBT positivity. In SLE patients there were no differences in LBT positivity, anti-dsDNA antibodies and complement consumption between groups.
Our study implies that the presence of speckled ANA in keratinocytes in LBT may be useful in the diagnosis of MCTD and in the prognosis of renal involvement, especially in SLE patients.