SUMMARYPemphigus foliaceus is an autoimmune blistering skin disease mediated by autoantibodies directed against desmoglein 1 and occurs as a sporadic form throughout the world, or as an endemic form called fogo selvagem in Brazil. Healthy subjects living in Brazilian endemic areas produce antidesmoglein 1 antibodies, suggesting the role of environmental factors in the initiation of the autoimmune response. Tunisia was described recently as an endemic area where the disease is characterized by its high rate among young people, especially women. An enzyme-linked immunosorbent assay using recombinant desmoglein 1 as antigen was used to detect antibodies against desmoglein 1 and calibrated with sera from 67 French healthy blood donors, 20 French pemphigus foliaceus patients and patients with other bullous skin diseases. When sera from 179 healthy Tunisian blood donors were tested, 31 (17%) were found positive. The desmoglein 1 binding activity of these 31 sera was confirmed in 10 cases by indirect immunofluorescence analysis and/or immunoblotting using human epidermal extract. Subclass analysis of antidesmoglein 1 antibodies showed that they were almost exclusively of the IgG2 subclass in positive normal sera and of IgG4 subclass in patients with PF. Thus, antibodies against desmoglein 1 are prevalent in normal subjects living in Tunisia which, along with their IgG2 isotype, suggests the role of the environment in the pathogenesis of this endemic type of pemphigus foliaceus and the need for additional factors to switch from a subclinical to a clinical form of the disease.

A systematic exploration of the V H 2/V U 12^13 variable domains of the anti-CD4 monoclonal antibody (mAb) 13B8.2 was performed by the Spot method to screen for paratope-derived peptides (PDPs) demonstrating CD4 binding ability. Nine peptides, named CB1 to CB9, were identified, synthesized in a cyclic and soluble form and tested for binding to recombinant soluble CD4. Among them, CB1, CB2 and CB8 showed high anti-CD4 activity. Competition studies for CD4 binding indicated that PDPs CB1, CB8, and the parental mAb 13B8.2 recognized the same complementarity determining region (CDR)3-like loop region. PDP CB1 was shown to mimic the biological properties of 13B8.2 mAb in two independent cellular assays, demonstrating inhibitory activities in the micromolar range on antigen presentation and human immunodeficiency virus promoter activation. Our results indicate that the bioactive CDR-H1 PDP CB1 has retained a significant part of the parental 13B8.2 mAb properties and might be a lead for the design of anti-CD4 peptidomimetics of clinical interest. ß

In the original article a mistake was made in the name of the fourth author. The correct name has been given above.