Selective loss of peripheral blood CD45RO + T lymphocytes correlates with increased levels of serum cytokines and endothelial cell-derived soluble cell adhesion molecules in patients with chronic idiopathic neutropenia of adults

Abstract

The present study was designed to investigate the hypothesis that selective loss of peripheral blood CD45RO+ T lymphocytes in patients with chronic idiopathic neutropenia of adults (CINA), previously reported from our laboratory, may be due to enhanced extravasation into the tissues. Serum levels of endothelial cell-derived soluble cell adhesion molecules (sELAM, sICAM and sVCAM), usually used as indicators of endothelial cell activation, were measured in 73 CINA patients and 32 healthy volunteers using a micro-ELISA method. We found that patients had markedly elevated concentrations of all three soluble cell adhesion molecules studied compared to the controls, and serum levels of sELAM, sICAM and, more importantly, sVCAM correlated inversely with the numbers of both CD4+/CD45RO+ and CD8+/CD45RO+ T cell subsets. Using a micro-ELISA method, we also measured serum levels of two endothelial cell activators, interleukin (IL)-1beta and TNF-alpha, and found that CINA patients had significantly higher cytokine concentrations than control subjects. Serum levels of IL-1beta and TNF-alpha correlated positively with the values of all three soluble cell adhesion molecules and inversely with the numbers of CD4+/CD45RO+ and CD8+/CD45RO+ T cell subsets. Moreover, we measured serum levels of the chemokine RANTES by a micro-ELISA technique and found that CINA patients also had elevated concentrations of the molecule compared to controls. Serum RANTES correlated positively with IL-1beta, TNF-alpha, sICAM, sVCAM and sELAM and inversely with the numbers of both CD4+/CD45RO+ and CD8+/CD45RO+ T cell subsets. These findings strongly suggest that CINA patients have an activated endothelium to which CD45RA+ and CD45RO+ T cells tether and roll, but firm adhesion and transendothelial migration are restricted to CD45RO+ T cell subsets, as endothelial VCAM-1 interacts with the vascular leukocyte adhesion molecule-4 (VLA-4) constitutively expressed on CD45RO+ but not on CD45RA+ T cells. Subsequent subendothelial and tissue migration of CD45RO+ T cells may be facilitated by the chemokine RANTES, which acts mainly on CD45RO+ T cells. We concluded that selective loss of peripheral blood CD45RO+ T lymphocytes in CINA patients is probably due, at least in part, to enhanced extravasation of both CD4+/CD45RO+ and CD8+/CD45RO+ T cell subsets into the tissues.