Progressive Multifocal Leukoencephalopathy in Primary Immune Deficiencies: Stat1 Gain of Function and Review of the Literature.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a rare, severe, otherwise fatal viral infection of the white matter of the brain caused by the polyomavirus JC virus, which typically occurs only in immunocompromised patients. One patient with dominant gain-of-function (GOF) mutation in signal transducer and activator of transcription 1 (STAT1) with chronic mucocutaneous candidiasis and PML was reported previously. We aim to identify the molecular defect in 3 patients with PML and to review the literature on PML in primary immune defects (PIDs). METHODS: STAT1 was sequenced in 3 patients with PML. U3C cell lines were transfected with STAT1 and assays to search for STAT1 phosphorylation, transcriptional response, and target gene expression were performed. RESULTS: We identified 3 new unrelated cases of PML in patients with GOF STAT1 mutations, including the novel STAT1 mutation, L400Q. These STAT1 mutations caused delayed STAT1 dephosphorylation and enhanced interferon-gamma-driven responses. In our review of the literature regarding PML in primary immune deficiencies we found 26 cases, only 54% of which were molecularly characterized, the remainder being syndromically diagnosed only. CONCLUSIONS: The occurrence of PML in 4 cases of STAT1 GOF suggests that STAT1 plays a critical role in the control of JC virus in the central nervous system.

Epigenetic modifications and improved regulatory T-cell function in subjects undergoing dual sublingual immunotherapy.

BACKGROUND: Allergen-specific immunotherapy is the only mode of therapy that has been demonstrated to offer a cure in patients with IgE-mediated respiratory allergies. OBJECTIVE: We sought to demonstrate the safety and efficacy of timothy grass (TG) and dust mite (DM) dual sublingual immunotherapy (SLIT) and to begin to investigate the immune mechanisms involved in successful immunotherapy with multiple allergens. METHODS: The safety and efficacy of dual SLIT with TG and DM in children and adults with demonstrated allergies to TG and DM were investigated in a single-center, randomized, double-blind, controlled phase I study. Thirty subjects received either TG and DM dual SLIT (n= 20) or placebo (n = 10). Immune parameters were evaluated for differentiation of desensitized subjects from control subjects. RESULTS: Subjects treated with dual SLIT had decreased rhinoconjunctivitis scores (P < .001) and medication use scores (P < .001) and reduced responses to TG and DM allergen based on results of skin prick tests or nasal disk challenges (P < .01 and P < .001, respectively) compared with placebo-treated control subjects. An increase in TG- and DM-specific IgG(4) levels, reduced allergen-specific IgE levels, and subsequent basophil activation were observed in the active treatment group. Dual SLIT promoted allergen-specific suppressive CD4(+)CD25(high)CD127(low)CD45RO(+) forkhead box protein 3 (Foxp3)(+) memory regulatory T cells with reduced DNA methylation of CpG sites within the Foxp3 locus. CONCLUSION: The results of this pilot study suggest that dual SLIT could be an effective means to treat subjects with sensitivities to a variety of allergens and that long-term tolerance might be induced by epigenetic modifications of Foxp3 in memory regulatory T cells.