January 1999, Volume 23, Issue 1, Pages 63 – 69

Immunobiology

Comparison of monocyte-dependent T cell inhibitory activity in GM-CSF vs G-CSF mobilized PSC products AG Ageitos1, ML Varney1, PJ Bierman2, JM Vose2, PI Warkentin1 & JE Talmadge1,3 1Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA     2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA     3Correspondence: Dr JE Talmadge, Department of Pathology and Microbiology, University of Nebraska Medical Center, 600 South 42nd Street, Omaha, NE 68198-5660, USA

Keywords

monocytes;   stem cell mobilization;   T cells;   GM-CSF;   G-CSF

Abstract

This study compares the immune properties of peripheral blood stem cell (PSC) products mobilized with different hematopoietic growth factors (HGFs) as well as apheresis products and peripheral blood leukocytes (PBL) from normal individuals. We found that monocytes in mobilized PSC products appear to inhibit T cell function independent of whether granulocyte colony- stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) was used for mobilization. In addition, the GF used to mobilize the stem cell product may be less important to the CD4:CD8 ratio than the extent of prior chemotherapy, as we found an inverse correlation between chemotherapy and the CD4:CD8 ratio. In other observations, all apheresis products, whether mobilized or unmobilized, contained significantly more monocytes compared to normal PBL. The mononuclear cells (MNC) from G-CSF or GM-CSF mobilized PSC products had a similar T cell phytohemagglutinin (PHA) mitogenic response that was significantly lower (P = 0.001 and P = 0.005, respectively) than non-mobilized apheresis products. We also examined the T cell inhibitor (TI) activity of the MNC from the PSC products for allogeneic lymphocyte proliferation and found that PSC products significantly reduced the proliferation of allogeneic PBL to PHA. A significant correlation (P = 0.001, r = 0.517) between the frequency of monocytes and TI activity also was observed.

Received 29 May 1998; Accepted 11 August 1998

^© Macmillan Publishers Ltd 1997