title: Failure to detect a prozoning anti-Fya in the serum of a chronically transfused patient.
abstract: A 78-year-old white male presented to our facility with vascular occlusion. He was Group A, D-positive, with a negative indirect antiglobulin test (antibody screen). Records at our facility, 4 years prior to this admission, indicated a history of anti-Fya, and Fy(a-) units were provided. A referring hospital had transfused the patient for "chronic anemia" (1-3 units weekly for 2 years), and he had received eight units (untested for Fya) immediately prior to his transfer to our facility for acute hemorrhage. Only the presence of anti-JH in the Serum was documented. To detect possible immune red cell destruction, the patient was monitored by our facility at 24-hour intervals with a direct antiglobulin test and antibody screen. On day 4, a 4+ anti-Fya was identified in the serum and the DAT was negative. Three days later anti-K was also identified. The serologic picture remained unchanged for 10 days, when the DAT became positive. Concurrently, a mixed-field Fya typing (on the patient's chloroquine diphosphate-treated cells) was detected. Repeat Fya typing of all units transfused at our facility confirmed their FY(a-) status. From the day of admission, eluates on every sample, using a low pH technique, showed anti-Fya specificity. Titration of the anti-Fya in the sample drawn on admission reacted from a dilution of 4 through 2,048 but not in neat serum. Although a prozoning phenomenon is uncommon, this case study suggests that a prozoning anti-Fya present in the patient's serum may have been a contributing factor to his "chronic anemia."
authors.affiliation: Blood Bank, Humana Hospital-Suburban, 4001 Dutchman's Lane, Louisville, KY 40207, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Sizemore
authors.forename: T D
authors.initials: TD
authors.lastname: Sammons
authors.forename: J N
authors.initials: JN
authors.lastname: Clanton