HETEROGENEITY IN CELLULAR AND CYTOKINE PROFILES FROM MULTIPLE SAMPLESOF TISSUE SURROUNDING REVISED HIP PROSTHESES

Previous studies have attempted to define the biologic properties of t he bone-implant interface using a single specimen harvested from the p eriprosthetic tissues. The purpose of this study was to examine the he terogeneity in cellular and cytokine profiles of multiple samples take n from the tissues surrounding revised hip prostheses. Clinical and ra diographic data for nine patients undergoing surgical revision was gat hered prospectively. Three tissue samples were taken systematically fr om the acetabular and/or femoral bed. Morphologic characteristics of t he tissues were assessed using hematoxylin and eosin-stained sections. Immunohistochemical staining was performed using monoclonal antibodie s to identify macrophages (EMB11 and CD68); activated macrophages (Leu M3); total T lymphocytes (Leu 4 and T11); T-helper lymphocytes (Leu 3 A and CD4); cytotoxic/suppressor T lymphocytes (Leu 2A and CD3); and f ibroblasts (5B5). In situ hybridization was used to identify the mRNA for specific proteins: interleukin (IL)1 alpha and -beta, IL-2, IL-6, transforming growth factor beta, tumor necrosis factor alpha (TNF alph a), platelet-derived growth factor alpha (PDGF alpha), and interferon gamma. A quantitative assessment was performed for each section by cal culating the percentage of positively staining cells using a light mic roscope and grid-counting technique. A random effect analysis of varia nce was calculated to determine both the variance between samples with in each patient and the variance between different patients. Standard deviations contributed by sampling variance and patient variance were calculated and an F test was applied. Tissue samples taken from differ ent regions of the bone-prosthesis interface showed marked heterogenei ty in cellular and cytokine profiles. Critical F values indicating a s tatistically significant degree of variance between different tissue s amples were exceeded for macrophages, cytotoxic/suppressor T lymphocyt es, and T-helper lymphocytes. The cytokine profile was significantly d ifferent for IL-2, PDGF alpha, and TNF alpha. This tissue heterogeneit y may be due to different mechanical and biologic environments along t he bone-prosthesis interface. Thus, caution must be exercised in defin ing the biologic properties of the tissue surrounding revised prosthes es according to a single biopsy. (C) 1996 John Wiley & Sons, Inc.