The Importance of the Number of Transplanted Cells with Dipeptidyl Peptidase-4 Expression on the Hematopoietic Recovery and Lymphocyte Reconstitution in Patients with Multiple Myeloma after Autologous Hematopoietic Stem-Cell Transplantation
Authors: Kopinska Anna , Krawczyk-Kulis Malgorzata , Dziaczkowska-Suszek Joanna , Bieszczad Katarzyna , Jagoda Krystyna , Kyrcz-Krzemien Slawomira 
Published: October 2019

Abstract
Introduction
Autologous hematopoietic stem cell transplantation (AHSCT) remains the treatment of choice in multiple myeloma (MM) patients (pts). In earlier research it has been suggested that the expression of dipeptidyl peptidase-4 (DPP4, CD26) influences both the homing and lymphocyte reconstitution after AHSCT in pts with lymphoproliferative neoplasms. The aim of the study is to investigate the effect of transplanted CD26 positive cells of the hematopoietic recovery and lymphocyte reconstitution in MM pts after AHSCT.
Patients and methods
Forty eight pts with MM with median age 56 (range 21-76) were undergoing AHSCT in our center in years 2011-2013. Conditioning regimen was Melphalan 200. Number of all CD26+ cells, CD26+ lymphocytes, CD26+ monocytes and CD26+ and CD34+ cells were measured in harvested material. Number of lymphocyte's subpopulations (all lymphocytes CD3+, helpers CD3+CD4+, suppressors CD3+CD8+, natural killer (NK) CD3-CD16+CD56+, cytotoxic NK CD3+CD16+CD56+, lymphocytes B CD3-CD19+) were measured in peripheral blood during regeneration period after AHSCT. In both flow cytometry was used. The hematopoietic regeneration was measured as following: the day of white blood cells' regeneration when WBC count reached >1,0x109/L, the day of granulocytes' regeneration when ANC >0,5x109/L and the day of platelets' regeneration when PLT >20x109/L.
Results
All pts successfully engrafted. The results of AHSCT are shown in table nr 1.
Table 1. The number of transplanted cells and regeneration during the procedure AHSCT in pts with MM. Parameter Median Range Mean Standard deviation Number of transplanted WBCx108/kg b.w. 4,26 0,73-18,8 5,43 4,36 Number of transplanted CD34+cells x106/kg b.w. 3,36 2,2-8,2 3,52 1,28 Number of transplanted CD26+ lymphocytes [109/L] 46,5 9-148 53,6 30,8 Number of transplanted CD26+ monocytes [109/L] 3,65 0-82 8,03 13,05 Number of all transplanted CD26+ cells [109/L] 50,42 9,6-213 62,5 23,2 Regeneration WBC >1x109/L (day) 13 10-20 13 2,64 ANC >0.5x109/L (day) 13 9-20 13,3 2,16 PLT >20x109/L (day) 14 11-20 14,1 2,18
As regards regeneration of hematopoietic cells after AHSCT it was shown that a higher number of transplanted CD26+ monocytes improves the reconstitution of suppressor (p=0,019) and NK lymphocytes (p=0,0237). A higher number of all transplanted CD26+ lymphocytes has a positive impact of the reconstitution of suppressor lymphocytes (p=0,0054), whereas a higher number of all transplanted the CD26+ cells improves the regeneration of cytotoxic NK (p=0,0126) and helper lymphocytes (p=0,0261). There were no confirmed adverse effects of the number of CD26+ cells on the hematopoietic regeneration0 and lymphocytes B reconstitution after AHSCT.
Discussion
Our research shows that the number of transplanted CD26-positive cells may improve immune reconstitution after AHSCT in patients with multiple myeloma, which was not clearly demonstrated before. As is well known faster lymphocyte reconstitution after AHSCT is associated with improved patient survival. Therefore, the greater the number of transplanted autologous CD26-positive cells may be associated with improved survival, which, however, needs further investigation.

Disclosures
No relevant conflicts of interest to declare.