Direct immunofluorescence on plucked hair outer root sheath can predict relapse in pemphigus vulgaris.

BACKGROUND

Prospective research is lacking on the utility of plucked hair outer root sheath direct immunofluorescence (ORS DIF) in the prediction of relapse in pemphigus vulgaris (PV) and the correlation of ORS DIF positivity with serum desmoglein antibody titers.

METHODS

We performed a prospective cohort study enrolling 80 PV patients in complete clinical remission at a tertiary care center in North India. Study participants underwent ORS DIF at baseline, which was repeated every 3 months. Skin biopsy DIF was done at study inclusion, repeated at 3 months, and upon clinical relapse. An antidesmoglein antibody titer was assessed concurrently with ORS DIF in a subset of patients. Patients on adjuvant therapy had their adjuvant therapy withdrawn either at the initial visit, at 3 months, or at a 6-month follow-up. Our objectives were to determine the association between positive ORS DIF and clinical relapse, the correlation between positive ORS DIF and skin biopsy DIF, and between positive ORS DIF and positive antidesmoglein antibody titers (when concurrently done).

RESULTS

Twenty-two patients (27.5%) had a clinical relapse. Baseline immunological markers significantly associated with relapse are ORS DIF positivity with IgG (16/36 [45.44%] P = 0.005) and C3 (12/29 [41.37%] P = 0.047) and greater intensity of baseline IgG and C3 positivity in ORS DIF (IgG, P = 0.002; C3, P = 0.033). Notably, a significant correlation was observed between baseline positive ORS DIF and skin biopsy DIF (IgG, ρ = 0.695; C3, ρ = 0.498). Positive ORS DIF strongly correlated with positive anti-Dsg3 antibody titers (φs = 0.815; P < 0.01). Early withdrawal of adjuvant immunosuppressant (within 3 months) (P = 0.007) and positive ORS DIF were also associated with relapse (P = 0.017).

CONCLUSION AND RELEVANCE

ORS DIF is a reliable predictor of PV clinical relapse and demonstrated robust correlations with skin biopsy DIF and antidesmoglein antibody titers. Periodic assessment of ORS DIF aids in determining new-onset positivity that heralds clinical relapse.