Engraftment of tonsillar mononuclear cells in human skin/SCID mouse chimera--validation of a novel xenogeneic transplantation model for autoimmune diseases

Pustulosis palmaris et plantaris (PPP) has been considered as one of the typical tonsillar focal infections, based on the marked clinical improvement of the skin lesions after tonsillectomy. Despite the accumulation of data showing the clinical efficacy of tonsillectomy for this skin lesion, fundamental etiological and pathophysiological issues have yet to be addressed. One primary obstacle hindering investigators has been the lack of an appropriate animal model for this human skin disorder. In the early stage of PPP, it has been reported that lymphocytes, predominantly CD4+ T lymphocytes, infiltrate the palmar and plantar skins. However, the origin and mechanism of infiltration by these lymphocytes is not clear and there are very few reports on whether tonsillar mononuclear cells react directly with the skin. We have been intrigued by the ability to engraft human cells onto severe combined immunodeficiency (SCID) mice, together with the opportunity for long-term graft survival and ability to adoptively transfer various human immunocompetent cells. In this review, we addressed the existing deficiencies in our understanding of the relationship between tonsils and PPP by using emerging transplantation technology involving SCID mice.