〈Background and Methods〉: High-grade fever prior to engraftment without any apparent signs of infection, mimicking hyperacute GVHD or engraftment syndrome, is often observed in patients who undergo cord blood transplantation (CBT). This “pre-engraftment immune reaction (PIR)” peaks at around day 9 of CBT, and is often accompanied by high-grade fever, skin rash and weight gain. Although PIR responds well to corticosteroid therapy, the prolonged use of steroid often causes an increased incidence of infectious complications, leading to significant treatment-related mortality, particularly in the elderly. It has been speculated that cytokines induced by the initial immune/inflammation reaction are the primary cause of PIR, but no confirming data are available. To clarify this point, we evaluated the protein expression profile of serum in CBT recipients using a surface-enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF MS) system and found marker candidates in PIR after CBT.

〈Results〉: Thirty-eight blood samples were taken from 13 CBT recipients at 3 different occasions, i.e.

  1. afebrile period prior to PIR onset,

  2. onset of fever and

  3. resolution of fever, to compare the relative protein expression levels.

Samples were analyzed in 56 spectra by changing the elution conditions with 4 kinds of chips (IMAC30, CM10, H50, Q10), 5 different rinse conditions and 3 kinds of energy absorption molecules. Six candidate protein peaks that commonly increase at the time of PIR with molecular masses of 8611Da, 8642Da, 11452Da, 11512Da, 11539Da and 11669Da were identified. The 11kDa protein peaks that bind to a Q10-anion exchange chip were selected for further analysis. Two 11kDa protein peaks were eluted at pH9 and pH4, but since the proteins eluted at pH4 included albumin which overlapped the candidate protein peak, the elution fraction at pH9 was used for purification and identification. Proteins eluted at pH9 were separated by SDS-PAGE. After in-gel digestion of the 11kDa band by trypsin, the digested peaks were analyzed by PCI Qstar MSMS and the protein was determined using the ProFound database. The results revealed that the 11kDa protein was an N-terminal portion of serum amyloid A (SAA). The SAA level was measured by ELISA in the same sample that was assessed by SELDI-TOF MS. The mean SAA level prior to fever onset was 14 (3–51) μg/mL, and this increased to 883 (40–2470) μg/mL at the time of PIR and decreased to 45 (8–126) μg/mL after resolution of the fever.

〈Conclusion〉: A specific marker for PIR after CBT was identified by an SELDI-TOF MS system. SAA increased by 10- to 100-fold at the time of PIR, and thus may become a useful tool for the diagnosis of PIR.

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Topics:
biological markers, engraftment, serum amyloid a protein, umbilical cord blood transplantation, weight gain, gel, fever, albumins, anions, cytokine

Disclosure: No relevant conflicts of interest to declare.

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2006, The American Society of Hematology
2006
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