The explanation for being familiar with this appearance is that evaluating IgG4 deposition in a cost-effective manner with traditional DIF is of diagnostic value, especially in undiagnosed clinically active smoldering pemphigus cases despite this treated with inadequate immunosuppression and thus having equivocal results of serum testing with ELISA techniques and DIF testing for just IgG and C3 deposition, as it enables the detection of Th2-mediated phenomena characteristic for the active stage of pemphigus . mucocutaneous pemphigus vulgaris only desmoglein 1 clustering correlates with nonacantholytic intercellular widening between desmosomes. The sequestration of desmogleins from desmosomal components, fitting in with the desmoglein non-assembly depletion hypothesis, as well as targeting non-junctional desmogleins that are no longer available to be incorporated into desmosomes structures are processes leading this way to the disturbed assembly of desmogleins-depleted desmosomes . The issue is still more complex, as regarding IIF on monkey esophagus it should be noted that pemphigus-like antibodies of IgG class misleadingly can give a granular appearance, instead of a pemphigus-characterizing honeycomb appearance, whereas such antibodies are not detectable in IgG4 subclass and such a finding is not related to the presence in serum of examined antibodies reacting with blood groups antigens expressed in the substrate tissue  (Figure 2). Obvious explanation might be that the substrate influences fluorescence images. Open in a separate window Figure 2 Pemphigus-like serum antibodies of IgG class giving granular appearance detected with IIF on monkey esophagus (A) in a WQ 2743 middle-aged female with long-standing psoriasis taking oral methotrexate and oral cyclosporine simultaneously which induced massive oral erosions clinically suggesting mucosal-dominant pemphigus vulgaris. Using AB absorbent (Euroimmun, Germany), developed with an aim to pre-absorb serum antibodies to blood groups antigens, did not affect the result when testing for IgG antibodies was done in the examined serum (B), whereas there were no pemphigus-like serum antibodies of IgG4 subclass detected both with (C) and without AB absorbent which stresses the diagnostic significance of evaluating IgG4 antibodies if one still uses IIF on monkey esophagus in the differential diagnosis of pemphigus However, in light of the above, the intriguing question arises why IgG4 deposits in DIF are less continuous than IgG ones at the same magnification. The explanation may be that IgG gives more disease-nonspecific background staining involving less desmoglein-rich areas on a keratinocytes surface whereas IgG4 is responsible for more pemphigus-specific pathology staining desmoglein-rich desmosomes and extradesmosomal desmogleins. This speculation requires investigational verification as putative non-desmoglein targets Rabbit Polyclonal to SCNN1D might be pathogenetically relevant . Putting aside detailed pathogenesis, we suggest that this dew drops on spider web appearance of IgG4 pemphigus deposits as newly described in depth here, that has WQ 2743 already been mentioned just incidentally by us in a PubMed accessible reference , should be known by both laboratory workers and dermatology clinicians dealing with pemphigus. The reason for being familiar with this appearance is that evaluating IgG4 deposition in a cost-effective manner with traditional DIF is of diagnostic value, especially in undiagnosed clinically active smoldering pemphigus cases despite this treated with inadequate immunosuppression and thus having equivocal results of serum testing with ELISA techniques and DIF testing for just WQ 2743 IgG and C3 deposition, as it enables the detection of Th2-mediated phenomena characteristic for the active stage of pemphigus . It is interesting in the context of IgG4-mediated autoimmune processes in pemphigus that some patients with IgG4-related disease experience a relapse following rituximab . The relapse of this kind might be related to the survival of low memory B cells after rituximab use WQ 2743 which was noticed in patients with pemphigus . Furthermore, in drug-induced pemphigus, the pattern of immunostaining of perilesional tissue may be used as a prognostic marker since the absence of patchy staining with an antibody to desmoglein 1 and 3 is considered an indicator of favorable prognosis . Finally, advanced imaging techniques such as atomic-force microscopy/scanning-force microscopy, multi-photon microscopy, super/high resolution techniques known under acronyms STED (STimulated Emission Depletion) and GSDIM/dSTORM (Ground State Depletion followed by Individual Molecule return/direct Stochastic Optical Reconstruction Microscopy) would expand our understanding of what is going on when pemphigus autoimmune recognition occurs on the surface of keratinocyte and, if adjusted to routine diagnostic use, provide novel appearances more precisely rendering reality. Conflict of interest The authors declare no conflict of interest..
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