Importante

Clin Exp Immunol 1995; 100:133-138

Selective recruitment of lymphocyte subsets to the inflamed appendix
K. S. SOO, C. A. MICHIE*, S. R. BAKER, J. H. WYLLIE & P. C. L. BEVERLEY* Department of Surgery, University College London Medical School and *Tumour Immunology Unit, Imperial Cancer Research Fund, London, UK

(Acceptedfor publication 12 December 1994)

SUMMARY Total lymphocyte countsand the distribution of lymphocyte subsets were determined in peripheral venous blood and appendiceal mononuclear cells from 60 patients who underwent appendicectomy for the clinical diagnosis of appendicitis. A significant peripheral lymphopenia was observed in the 46 patients with histologically confirmed acute appendicitis which was accompanied by an increase in the appendiceal lymphocyteconcentration. There was an even greater depletion of CD45RO+ (memory) T lymphocytes in peripheral blood and an increase in the inflamed appendix. Reciprocal changes were observed in the CD45RA + (naive) T lymphocyte subset. These changes were reflected in the local arterial and venous CD45RA and CD45RO T lymphocyte subsets. Proliferation studies showed an expanded functional repertoire of T lymphocytesin the inflamed appendix. Selective recruitment of memory T lymphocytes from the peripheral blood to the inflamed appendix was demonstrated.

Keywords appendicitis lymphopenia CD45 naive lymphocytes memory lymphocytes

INTRODUCTION Peripheral blood lymphopenia often accompanies sepsis. Lymphopenia has been shown to occur in acute appendicitis [1], acute diverticulitis [2] and acutepancreatitis [3]. We were interested to know the fate of lymphocytes which left the peripheral blood. Did they migrate to sites of inflammation? And was migration confined to certain subsets of lymphocytes? Acute appendicitis provides an unique opportunity to investigate these questions. It is common; approximately 250 appendicectomies are performed every year in our hospital. It occurs in all age groups andhas no gender differences. It is the only common acute inflammatory condition in which the inflamed organ is completely removed and available for analysis. Equally importantly, there are false positive diagnoses, making apparently normal appendices available for comparison. This clinical situation offers an opportunity to investigate lymphocyte traffic in acute inflammation. PATIENTS AND METHODSPatients

appendicitis, one had an urinary tract infection, while the remaining 13 had no demonstrable pathology and were classified as having non-specific abdominal pain. The project was approved by the Whittington Hospital ethics committee.
Lymphocyte sampling and preparation A 1 3-ml pre-operative venous blood sample was collected from each patient, of which 3 ml were placed in anEDTA-coated glass tube (Becton Dickinson, Oxford, UK) for automated full blood count on a Technicon H-1 automatic analyser. The residual 10 ml were placed in a heparin-coated endotoxin-free glass tube (Becton Dickinson). The heparinized blood samples were later diluted with two volumes of PBS. The distal 0-25 cm at the tip and the proximal 0 25 cm at the base of the appendices were removed for routinehistology. The rest of the appendices were laid open and left to stand for 2 h at room temperature in culture medium (RPMI 1640) containing 5% complement-depleted fetal calf serum (FCS), 4mM glutamine, 100 U/ml penicillin and 100 jg/ml streptomycin. Cells were removed from the appendices by blunt dissection in sterile Petri dishes containing culture medium. Histological examination of residual tissueafter this procedure confirmed the efficient and complete harvesting of mononuclear cells from the appendices. The volumes of appendices were measured by fluid displacement before and after cell collection. Cell counts were carried out in a haemocytometer. The diluted blood and the appendiceal cells were layered onto Ficoll-Paque (Pharmacia, Uppsala, Sweden) and centrifuged at 250g for 25 min at...