  We consider certain line defect operators in five-dimensional SUSY gauge
theories, whose interaction with the self-dual instantons is described by 1d
ADHM-like gauged quantum mechanics constructed by Tong and Wong. The partition
function in the presence of these operators is known to be a generating
function of BPS Wilson loops in skew symmetric tensor representations of the
gauge group. We calculate the partition function and explicitly prove that it
is a finite polynomial of the defect mass parameter $x$, which is an essential
property of the defect operator and the Wilson loop generating function. The
relation between the line defect partition function and the qq-character
defined by N. Nekrasov is briefly discussed.
