Prospective Evaluation of Proteomic Screening with An Agvhd-Specific Proteomic Pattern MS-17.

Abstract 2246

Poster Board II-223

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for many hematologic malignancies or hematopoietic dysfunction syndromes in adults, but the application is still limited due to major complications, such as severe graft versus host disease (GvHD) and infectious complications. Diagnosis GvHD is based on clinical features and biopsies, a non-invasive, unbiased laboratory test using proteomics was published previously and evaluated in a multicenter setting (Weissinger et al., 2007). In order to maintain good quality data of the proteomic pattern data and due to the fact that the electrospray ionization time of flight mass spectrometer (ESI-TOF) from ABI (mariner) is no longer produced, we applied a more sensitive mass spectrometer (MS; ESI-TOF/Bruker). In order to validate the quality of the data produced with the Bruker, ESI-TOF was used since December 2007 in parallel to the mariner. Our first and previously published “aGvHD-specific pattern” (Weissinger et al., 2007) was used to evaluate and improve the pattern with the more sensitive decreased (6) or increased (11) signal intensity in patients with GvHD grade II to IV. Patients post HSCT and patients with GvHD grade I have the same pattern. In addition, the MS-17-pattern yielded at least comparable if not superior results to the previous one yielding sensitivities around 95% and specificity about 80%.

To date the proteomic pattern specific for aGvHD MS17 was evaluated blindly on 400 samples collected from about 90 patients undergoing allo-HSCT at MHH since Dec. 2007.

The peptide pattern MS-17 consists of 17 peptides - either absent/decreased (6) or present /increased (11) in aGvHD grade II to IV when compared to patients with clinical aGvHD grade I or without GvHD. Prospective and blinded evaluation of the patients included in this parallel diagnostic study revealed the correct classification of patients developing aGvHD about 7 days prior to the development of clinical signs and symptoms for aGVHD with a sensitivity and specificity of about 85%. Sequencing 3 of the 17 markers yielded the following results:

Peptide No 5: Albumine fragment (N-terminus); Peptide No 7: ψ2 microglobulin; Peptide No 10: fragment of CD99 (MIC2; a single-chain type-1 glycoprotein). CD99 and β-2 microglobulin are particulary interesting because of their involvement in immune responses, both being expressed on leukocytes and CD 99 especially on thymocytes with involvement in apoptosis of double positive T-cells and binding cyclosporin A. Data on the pattern, signal intensity (3 dimension, mass and charge are shown in Figure 1)