This paper (Kim, J., & Unger, S. (2010). Human milk banking. Paediatrics & Child Health, 15(9), 595–598) answers the question of whether or not donated milk contains immune system bonuses. It turns out that the pasteurization of milk results in the loss of pretty much all immune benefits, as the authors conclude that “along with inactivation of all viruses and most bacteria through pasteurization, all beneficial immune cells are also inactivated”. This is shown through referencing other papers and reviewing the evidence.