Peripheral blood stem cell harvests from G-CSF-stimulated donors contain a skewed Th2 CD4 phenotype and a predominance of type 2 dendritic cells.
OBJECTIVE
To assess the numbers and function of dendritic cell (DC) subsets and T helper cells in bone marrow (BM) and peripheral blood stem cell (PBSC) harvests.


METHODS
DC subsets in stem cell grafts were analyzed using three-color flow cytometry. Intracellular cytokine staining and the staining of IL-12Rbeta2 were used for determining the proportion of Th1-, Th2-, and IL-12-producing DC in the grafts. The ability of DC1 and DC2 to induce T-cell proliferation and cytokine secretion were studied using thymidine incorporation and ELISA techniques.


RESULTS
PBSC recipients received a significantly higher number of DC2 than BM recipients and a lower proportion of IL-12-producing DC. Purified DC1 from both BM and PBSC grafts were capable of inducing proliferation of allogeneic T cells and also induced a predominant Th1 response when cultured with CD4(+)/CD45RA(+) cells. In contrast, DC2 induced a predominant Th2 cytokine response. PBSC grafts contained a higher number of both Th1 and Th2 cells compared to BM grafts; however, as a consequence of the increased number of Th2 cells the ratio of Th1:Th2 cells in PBSC grafts was 1.1:1 compared to 9.8:1 in BM. Furthermore, following in vitro activation of T cells, PBSC grafts contained a lower proportion of IL-12Rbeta2(+) T cells.


CONCLUSIONS
G-CSF does not have a direct effect on DC function but acts to increase the numbers of DC2 in the blood of PBSC donors. This is associated with a higher proportion of Th2 cells present in PBSC grafts and T cells in PBSC grafts were less likely to develop a Th1 response following in vitro activation.
Klangsinsirikul
Phennapha
P
Division of Haematology, School of Clinical Laboratory Sciences, The University of Nottingham, Nottingham, UK.
Russell
Nigel H
NH
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D016130:Immunophenotyping; D018664:Interleukin-12 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051381:Rats; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology*; D014019:Tissue Donors; D020858:Tissue and Organ Harvesting / Q000379:methods; D014184:Transplantation, Homologous
D016179:Granulocyte Colony-Stimulating Factor; D018664:Interleukin-12