Danny Ainge says in the 26 years he's been playing and working for the Celtics ... he's "never" heard any racist remarks from fans at TD Garden -- but he did say he's taking Kyrie Irving's comments "seriously."
If you missed it ... Irving implored Celtics fans to treat him with respect when his Nets team arrives in Boston for its playoff games this weekend, insinuating he's been called racist things at the Celts' arena in the past.
But when Ainge was asked to comment on that on the 98.