Lupus band test.

The lupus band test (LBT) is a direct immunofluorescent technique for demonstrating a band of localized immunoglobulins at the dermal-epidermal junction in the skin of patients with lupus erythematosus (LE). Studies have shown immunoglobulins and complement at the dermal-epidermal junction in systemic (involved and uninvolved skin) and in discoid (involved skin only) LE. It is essential that the appropriate skin site be selected for biopsy; ie, involved or uninvolved skin, light-exposed or light-protected skin. The proper location of the biopsy site is determined by whether the LBT is intended for diagnostic or prognostic purposes. From a diagnostic standpoint, the LBT is a very sensitive and specific test for LE. In addition, this procedure has considerable value as a prognostic test for a patient with an established diagnosis of LE.