Purpose Vasculitis is a refractory disease with no established treatment. Therapeutic effect of gamma globulin (IgG) in high dose therapy (IVIg) has been reported (1). IgG preparation which depends on human-derived material, is not completely safety, and supply amount of it is finite. Development of recombinant gamma globulin having the same effect has been requested.
Methods We constructed a library of recombinant single chain fragment of variable region (hScFv) of IgG from the constitution of VH-CH1-hinge from peripheral blood lymphocytes of healthy volunteers. One thousand recombinant hScFv clones were analyzed in base sequence, and selected by having the correct structure of hScFv. Selected clones were mixed and cultured, and induced hScFv proteins were administered to spontaneous vasculitis mouse model SCG/Kj to evaluate therapeutic effects.
Results From the base sequence analysis of 1,000 clones, we obtained 245 clones having VH-CH1-hinge structure, then a library having 204 clones was established. All 204 clones were mixed and cultured to induce hScFv proteins. A purified preparation was administered into SCG/Kj mice. The hScFv administration at a concentration of 1/20 of the large amount of IgGs preparation showed same effect for suppression of glomerular crescent formation and a refinement of the peripheral blood cell was observed in hScFv administration groups. Also, a biomarker MPO-ANCA titer remarkably decreased at administration dose of IVIg in 1/10.
Conclusions The hScFv protein mixture showed therapeutic effects with 1/10 – 1/40 of IVIg in administration to SCG/Kj mouse. It seems to be a development possibility to actual preparation as recombinant IgG.

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Myeloperoxidase (MPO) is a subset of anti-neutrophil cytoplasmic antibodies (ANCA) and patients with this disease are highly susceptible to infection. Intravenous immunoglobulin (IVIg) therapy is considered beneficial for individuals with weak immune systems or for patients with other diseases who need to ward off infections. It has also demonstrated efficacy in suppressing disease activity in MPO-ANCA RPGN. The purpose of this study is to gain an understanding of how IVIg therapy helps to alleviate MPO-ANCA RPGN by shedding light on the mechanism of the treatment.
Cytokines/chemokines have been implicated in the pathogenesis of MPO-ANCA RPGN, therefore we determined patients’ plasma cytokine/chemokine levels before and after IVIg therapy using 27 plex and 12 plex array to observe any important changes. Therapy was supplied in two dosages, full and mini dose. We observed that post-treatment levels of RANTES, IL-1α, IL-2Ra, L-3, IL-18, CTACK, HGF, M-CSF, MIG, SCF and TNF-β decreased from their pre-treatment levels in both full dose and mini dose patients. These results suggest that these cytokines and chemokine become highly activated and are closely connected to acute MPO-ANCA nephritis, and that the efficacy of IVIg therapy is due to a reduction in these highly activated cytokine/chemokines.

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Phagocytes had been very difficult to deal with, because they have a small number in the peripheral blood and short life span. However, neonatal phagocyte screening with TAXscan in addition to NGS (next generation sequencer) will make it simple and precise to find their functional and molecular background and new aspect of phagocyte disorders will be explored in a near future.

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