21 CFR §1271.50

1. (a)Determination based on screening and testing. If you are the establishment responsible for making the donor-eligibility determination, you must determine whether a donor is eligible based upon the results of donor screening in accordance with § 1271.75 and donor testing in accordance with §§ 1271.80 and 1271.85. A responsible person, as defined in § 1271.3(t), must determine and document the eligibility of a cell or tissue donor.
2. (b)Eligible donor. A donor is eligible under these provisions only if:
   1. (1)Donor screening in accordance with § 1271.75 indicates that the donor:
      1. (i)Is free from risk factors for, and clinical evidence of, infection due to relevant communicable disease agents and diseases; and
      2. (ii)Is free from communicable disease risks associated with xenotransplantation; and
   2. (2)The results of donor testing for relevant communicable disease agents in accordance with §§ 1271.80 and 1271.85 are negative or nonreactive, except as provided in § 1271.80(d)(1).