UNUSUAL KINETICS OF WHITE CELL CLEARANCE IN TRANSFUSED MICE

Background: Donor white cells (WBCs) in blood transfusions are respons ible for complications in recipients, including alloimmunization, graf t-versus-host disease (GVHD), and virus transmission and reactivation. The recent use of sequence-specific polymerase chain reaction assays to monitor the kinetics of clearance of donor WBCs in transfused human s and dogs found transient recirculation of donor lymphocytes on Days 3 to 5 after transfusion; this Presumably reflected an abortive GVHD r eaction to ma]or histocompatibility complex-incompatible recipient cel ls, after which donor WBCs were cleared to undetectable levels. Study Design and Methods: This study sought to develop a murine model to fur ther characterize the kinetics and major histocompatibility complex re striction of donor WBC clearance. A sensitive murine Y chromosome-spec ific polymerase chain reaction assay was developed and applied to seri al blood samples collected after transfusions of allogeneic blood to n aive inbred, primed inbred, and outbred mice, as well as after transfu sions of gamma-radiated blood to naive inbred mice. Results: in inbred mice, both naive and primed to the allogeneic blood donor, transfused WBCs were not cleared to undetectable levels for more than 1 month af ter transfusion. Transfused outbred mice also showed prolonged donor W BC survival, although at lower levels than inbred mice. There was no e vidence of GVHD in either inbred or outbred mice, and gamma radiation had no significant impact on donor WBC persistence. Conclusion: These results contrast with the rapid clearance of donor WBCs observed in hu mans and dogs. The immunologic basis for this discrepancy remains uncl ear. Caution should be exercised in any extrapolation to humans of con clusions drawn from results in transfused mice.