THE SCID-HU MOUSE AS A TOOL IN IMMUNOTOXICOLOGICAL RISK ASSESSMENT - EFFECTS OF 2-ACELYL-4(5)-TETRAHYDROXYBUTYL-IMIDAZOL (THI) AND DI-N-BUTYLTIN DICHLORIDE (DBTC) ON THE HUMAN THYMUS IN SCID-HU MICE

SCID mice engrafted with human fetal thymus and liver tissue fragments (SCID-hu mice) are currently considered as a new tool in human immuno toxicoiogical risk assessment, Testing of various immunotoxicants exer ting thymotoxicity via different intrathymic target cell types is nece ssary for validation of this model. Therefore, SCID-hu mice were expos ed to -acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)-imidazole (THI), the im munotoxic component in the food additive, Caramel Colour III, or the o rganotin compound, di-n-butyltin dichloride (DBTC). Histopathological examination of the human thymus grafts of SCID-hu mice either exposed to THI or to DBTC showed a reduction in the relative size of the thymu s cortex, an effect also described in rodents. These results indicate that the human thymus is a target for the immunotoxic action of both T HI and DBTC, In addition, they indicate the promising potential of the SCID-hu mouse model as a tool for human immunotoxicological risk asse ssment.