HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by van Lent, P.L.E.M. Articles by van den Berg, W.B. Search for Related Content PubMed PubMed Citation Articles by van Lent, P.L.E.M. Articles by van den Berg, W.B.

(Journal of Leukocyte Biology. 2001;70:708-714.)
© 2001 by Society for Leukocyte Biology

Uptake of apoptotic leukocytes by synovial lining macrophages inhibits immune complex–mediated arthritis

P.L.E.M. van Lent^*, R. Licht, H. Dijkman, A.E.M. Holthuysen^*, J.H.M. Berden and W.B. van den Berg

Division of Rheumatology, University Medical Centre Nijmegen, the Netherlands,
^* Division of Nephrology, University Medical Centre Nijmegen, the Netherlands,
Division of Pathology, University Medical Centre Nijmegen, the Netherlands

Correspondence: P.L.E.M. van Lent, Division of Rheumatology, University Medical Center Nijmegen, Geert Grooteplein 26-28, 6500 HB Nijmegen, the Netherlands. E-mail: p.vanlent{at}reuma.azn.nl.

Previously we have shown that synovial lining macrophages (SLMs) determine the onset of experimental immune complex–mediated arthritis (ICA). During joint inflammation, many leukocytes undergo apoptosis, and removal of leukocytes by SLMs may regulate resolution of inflammation. In this study we investigated binding and uptake of apoptotic leukocytes by SLMs and its impact on the onset of murine experimental arthritis. We used an in vitro model to evaluate phagocytosis of apoptotic cells on chemotaxis. Phagocytosis of apoptotic thymocytes resulted in a significant decrease (58%) of chemotactic activity for polymorphonuclear neutrophils (PMNs). If apoptotic cells were injected directly into a normal murine knee joint, SLMs resulted in a prominent uptake of cells. After ICA induction, electron micrographs showed that apoptotic leukocytes were evidently present in SLMs on days 1 and 2. Injection of apoptotic leukocytes into the knee joint 1 h before induction of ICA significantly inhibited PMN infiltration into the knee joint at 24 h (61% decrease). This study indicates that uptake of apoptotic leukocytes by SLM reduces chemotactic activity and inhibits the onset of experimental arthritis. These findings indicate an important mechanism in the resolution of joint inflammation.

Key Words: joint inflammation • immune complexes • synovium • apoptotic cells • synovial lining macrophages • chemotaxis