In systemic lupus erythematosus, the 'lupus band test' (LBT) is positive. In sun-exposed normal skin of SLE patients, what immunoreactants are typically deposited at the DEJ?
- A IgG, IgM, IgA, and C3 (multiple immunoglobulins — 'full house') ✓
- B IgG only
- C IgM only (natural immunoglobulin)
- D C3 and C5b-9 (membrane attack complex) without immunoglobulins
Correct answer: A. IgG, IgM, IgA, and C3 (multiple immunoglobulins — 'full house')
Explanation
The lupus band test shows granular deposition of multiple immunoglobulins (IgG, IgM, IgA) and complement (C3, C1q) at the DEJ in a 'full house' pattern. This is seen at the DEJ in both lesional and non-lesional sun-exposed skin in SLE (systemic), differentiating it from CCLE/DLE (positive only in lesional skin). The 'full house' pattern is pathognomonic of SLE. In MCTD and mixed connective tissue diseases, the band is weaker and immunoglobulin pattern may differ.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.