A transplant recipient may develop a hemolytic anemia mediated by lymphocytes imported with the transplant. The hemolysis is caused by alloantibodies to an antigen that lacking in the donor but present in the recipient. This is termed the passenger lymphocyte syndrome (PLS).



(1) The recipient develops an immune hemolytic anemia with a positive DAT following the transplant (absent before).

(2) The eluted antibody targets an antigen on the recipient's RBCs.

(3) The donor is negative for the target antigen.


Antibodies have targeted:

(1) ABO antigens

(2) Rh antigens

(3) other antigens such as Jk(a)


Risk factors:

(1) large number of lymphocytes in grafted material

(2) previous sensitization of the donor to recipient antigens

(3) presence of some condition that helped the donor lymphocytes to evade host immune clearance


Differential diagnosis:

(1) delayed transfusion reaction (antibody corresponds to an antigen on donor RBCs that is absent on recipient's; occurs for a limited time)

(2) autoimmune hemolytic anemia

(3) other type of hemolytic anemia


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