NOVEL FUSED PYRIMIDINE DERIVATIVE

PROBLEM TO BE SOLVED: To provide a prophylactic and/or therapeutic agent for diseases associated with autoimmunity, immune deficiency diseases or neurodegenerative diseases, in particular a prophylactic and/or therapeutic agent for sepsis.SOLUTION: The prophylactic and/or therapeutic agent includes a compound of formula (I) or a salt thereof. In the formula (I), Ais formula (A) or (B); Ais the formula (B) or the like when Ais the formula (A); Qis -NRRor the like; Rand Rare each a hydrogen atom, 1-10C alkyl or the like; Alkis a single bond or the like; X is a single bond or the like; Ris 1-10C alkyl or the like; Qis -NRRor the like; Rand Rare each a hydrogen atom, 1-10C alkyl or the like; Alkis a single bond or the like; Ar is allylene or the like; Y is a single bond, -O- or the like; Z is a single bond, -N(R)- or the like; Alkand Alkare each methylene or the like; nand nare each an integer of 1-3; and Ris a hydrogen atom, 1-10C alkyl or the like.