The detection and assay of integrins and soluble integrin ligands as an index of granulocyte function and mass after chemotherapy and stem cell tranplantation with haematopoietic growth factor administration
Date
2014-03-24
Authors
Wang, Xing
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Specific interactions between molecules expressed on the surface of
leukocytes and cell adhesion molecules on target cells are important
determinants of leukocyte function as well as playing a role in cell - cell
communication.Four main groups of adhesion molecules are recognized :
the integrinreceptor family; the immunoglobulin superfamily; selectins and
cadherins. The focus of the present study is on CD 1 lb/CD 18 ( Mac-1),
which belongs to integrin family, and its ligand ICAM-1, which belongs to
immunoglobulin family.
The s tudies which make up the body of this dissertation were designed to
investigate^ a ) the interaction of neutrophil adhesion molecule
CD 1 lb/CD 18 and its ligands and ( b ) to develop a marker of neutrophil
recovery and function after severe chemotherapy induced neutropenia
following either intensive but unsupported conventional dose consolidation
chemotherapy or high dose chemotherapy plus autologous stern cell
transplantation. These latter studies focussed on the soluble intercellular
adhesion molecule-1 (sICAM-1) .
The results of the studies presented in this dissertation may be summarized
as follows:
a ) Adhesion o f neutrophils to endothelial cells by a CDllb/CD18~
dependent mechanism
In this investigation the focus of interest was to study the adhesion of
normal neutrophils to vascular endothelial cells. While the factors including
the role of CD 11/CD 18 responsible for the interaction of neutrophils and
endothelium had been previously investigated there was still disagreement
about the role of CD 1 lb/CD 18. In this study an in-vitro method was
developed whereby adhesion to the ECV-304 cell line was used to
elucidate factors involved in neutrophil adhesion to vascular- endothelium.
The results showed that adhesion of unstimulated neutrophils to endothelial
cells is largely mediated by a GDI lb/CD 18-dependent cell : cell
interaction, probably through its ligand ICAM-1 on endothelial cells. In
addition, the results showed that normal serum contairrs a potent adhesive
factor, which promoted this interaction. This factor was identified as
complement fragment iC3b.
b ) Serum ICAM-1 concentration following conventional dose
consolidation chemotherapy for acute myeloid leukemia and after high
dose chemotherapy with autologous haematopoietic stem cell rescue
The first study had demonstrated an important role of CD 1 lb/CD 18 in
neutrophil adhesion. One of the important ligands of CDllb/CD18 is
ICAM-1. A soluble form of this ligand has previously been demonstrated.
The focus of this study was to elucidate receptor/ligand interactions. In this
investigation, serum concentrations of soluble ICAM-1 (sICAM-1) were
studied in patients with acute myeloid leukemia (AML) after conventional
dose consolidation chemotherapy and in AML and in breast cancer patients
following high dose chemotherapy with autologous haematopoietic stem
cell transplantation. Investigations were carried out at 3 phases following
treatment; during the chemotherapy induced neutropenic phase (neutrophil
counts < 0.5 x 109/1); during early recovery(neutrophil counts 0.5 x 109/1 -
1.0 x 109/1); and at recovery from neutropenia(neutrophil count 1.0 x 109/1 -
2.5x1071).
Results showed a significant elevation of serum levels of sICAM-1, above
normal, in both groups of patients during the neutropenic phase. A further
increase of sICAM-1 was found in conventional dose consolidation
chemotherapy treated AML patients during the post-neutropenia recovery
phases. By contrast, patients who were treated with high dose
chemotherapy plus autologous haematopoietic stem cell transplantation
showed a normalisation of sICAM-1 concentration during tire postneutropenic
recovery phases. These findings suggest that recovery
neutrophil function does not coincide with recovery of neutrophil count
following intensive but unsupported chemotherapy while there was rapid
recovery of neutrophil function occurred among patients who received
autologous haematopoietic stem cell support.
c ) Expression o f CDllb/CD18 on neutrophils in patients undergoing
consolidation chemotherapy for acute myeloid leukemia and in patients
undergoing h igh dose chemoth erapy and autologous haematopoietic stem
cell transplantation
This investigation dealt with the quantitative expression of CD 1 lb/CD 18
on neutrophils by flow cytometry in same population of patients
investigated in the previous study .
CDllb/CD18 expression on neutrophils during early and full neutrophil
recovery was normal in stem cell transplantation supported patients. By
contrast CD 1 lb/CD 18 expression was markedly decreased in patients who
received chemotherapy without stem cell support. These results together
with those of tire early study indicated that neutrophil abnormalities with
potentially important functional implications occur after neutrophil count
recovery following chemotherapy and that these defects may be
ameliorated by haematopoietic stem cell support.
In summary, the results presented here provide evidence that 1 )
CD 1 lb/CD 18 mediates the interaction of resting neutrophils to endothelial
cells, probably by recognizing ICAM-1 on endothelium. Complement
fragment iC3b promotes this interaction. 2 ) recovery of neutrophil
function does not coincide with recovery of neutrophil count following
intensive chemotherapy. sICAM-1 is considered as a sensitive marker of
neutrophil functional recovery.