Low-dose radiotherapy selectively reduces adhesion of peripheral blood mononuclear cells to endothelium in vitro.
OBJECTIVE
The anti-inflammatory effect of low-dose radiotherapy (LD-RT) still is not understood. The adhesion of leukocytes to endothelial cells (EC) of the vessel wall is the initial event of tissue invasion, and thus, crucially contributes to the regulation of inflammation. We investigated the influence of LD-RT on the adhesion process in vitro.


METHODS
Isolated peripheral-blood-mononuclear-cells (PBMC) were incubated with an activated murine endothelioma cell-line under shear conditions at 4 degrees C after irradiation with single doses between 0.1 and 10.0 Gy. Adherent cells were counted microscopically and compared to a non-irradiated control. In parallel, viability and expression of adhesion molecules, especially of L-selectin, and lineage-specific markers on the cell surface were determined by dye exclusion and cytofluorometry, respectively. Modulation of adhesion by soluble L-selectin was tested in the adhesion assay.


RESULTS
Radiation doses of 0.1-0.5 Gy reduced the adhesion of viable PBMC to EC in vitro by 70% of the control level 4 h after irradiation. Leukocytes showed a marked reduction of L-selectin expression after LD-RT. Soluble L-selectin can inhibit the adhesion of PBMC to EC.


CONCLUSIONS
The anti-inflammatory effect of LD-RT might, in part, be due to the reduction in the adhesion of PBMC to EC. This reduction in adhesion might be a consequence of the reduced expression of L-selectin on the surface of PBMC, and the inhibition of adherence by soluble L-selectin shed by PBMC in vitro.
Kern
P M
PM
Institute for Clinical Immunology and Rheumatology, University of Erlangen-Nürnberg, Universitätsstrasse 27, 91054, Erlangen, Germany.
Keilholz
L
L
Forster
C
C
Hallmann
R
R
Herrmann
M
M
Seegenschmiedt
M H
MH
D000328:Adult; D002448:Cell Adhesion / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D004730:Endothelium, Vascular / Q000502:physiology / Q000528:radiation effects*; D005260:Female; D006801:Humans; D019041:L-Selectin / Q000032:analysis / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000502:physiology / Q000528:radiation effects*; D008297:Male; D011879:Radiotherapy Dosage
D019041:L-Selectin