Spermatogenic immunoglobulin superfamily (SgIGSF) is a recently identified adhesion molecule, and the microphthalmia transcription factor (MITF) was essential for its expression in mast cells. Since the tg mutant allele is practically a null mutation of the MITF gene, cultured mast cells (CMCs) derived from (WB x C57BL/6)F-1 (F-1)-tg/tg mice did not express SgIGSF whereas CMCs from F-1-wild-type (+/+) mice expressed it abundantly. When cocultured with NIH/3T3 fibroblasts, F-1-tg/tg CMCs showed poor adhesion to NIH/3T3 fibroblasts. When injected intraperitoneally, F-1-tg/tg CMCs showed poor survival in the peritoneal cavity of mast cell-deficient F-1-W/W-r mice. SgIGSF was expressed in tg/tg CMCs ectopically through retroviral transfection and through expression of a transgene. The resulting tg/tg CMCs showed not only a better adhesion to NIH/3T3 fibroblasts but also a better survival in the peritoneal cavity than control F-1-tg/tg CMCs. SgIGSF-mediated adhesion seemed to play a role in the survival of CMCs in the peritoneal cavity. (C) 2004 Published by Elsevier Inc.