Lvad bridge to transplant. Question about antibody boxed labs?

Hello everyone. My husband has had two lvads. The first was a heart ware .And the second is a heart mate three. The first one ended up giving him a blood clot inside the lvad.  Two strokes and two brain bleeds. He has come back for the most part . Right side weakness, short term memory loss . Doing much better ,we are going on two years know. He is on the transplant list and we are now receiving what they call boxed labs to our home . They are checking his antibodies. Seem to be arriving about once a month. I was wondering if anyone else has or is receiving boxed labs. And if there is a meaning behind this . We go to the Cleveland Clinic Ohio. We are from Michigan. This is my first time on here ,We have read so many wonderful stories. . Good luck to everyone. Don & Sue