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In order to investigate the role of lymphocyte function-associated antigen 1 (LFA-1) in lymphocyte adhesion to endothelial cells (EC), we have studied the adhesion of a LFA-1-deficient lymphoblastoid cell line, ICH-KM, which has < 10% of the cell surface LFA-1 expressed on a normal lymphoblastoid cell line, ICH-BJ. The adhesion of ICH-KM cells to unstimulated EC was 49.9 ± 8-6% (mean ± SD) that of ICH-BJ cells. Moreover, phorbol ester-stimulated ICH-KM cells showed a considerably weaker increase in adhesion to unstimulated EC compared with ICH-BJ cells (mean ± SD increase in percentage adhesion, 3.8±2-3 compared with 18.5±8.0; P<0.025). In contrast, there was no significant difference between the enhanced adhesion of ICH-KM cells and ICH-BJ cells to interleukin-1 (IL-1)-stimulated EC. Thus ICH-KM cells showed a 22.7 ± 11.0 (mean ± SD) increase in percentage adhesion to IL-1-stimulated EC compared with the 24.8 ± 8-5 increase in percentage adhesion of ICH-BJ cells. Anti-LFA-1 monoclonal antibodies had no effect on the enhanced adhesion of ICH-KM and ICH-BJ cells to IL-1-stimulated EC but abolished the differences in adhesion between the two cell lines. The study therefore indicates that although a major part of unstimulated and phorbol ester-stimulated lymphocyte-EC adhesion is dependent upon LFA-1, the enhanced adhesion due to stimulation of EC with IL-1 is not dependent upon this molecule. The data therefore supports the existence of cytokine-inducible LFA-1-independent adhesion molecules for lymphocytes on EC. [ABSTRACT FROM AUTHOR]

E-selectin, a member of the selectin family, is believed to play an important role in mediating the initial adhesive events between leucocytes and the endothelium during inflammation. A monoclonal antibody against human E-selectin was found to cross-react with the porcine equivalent, a glycoprotein of 92 000 MW. Isolation of the cDNA for porcine E-selectin showed that it was 71% homologous with human E-selectin but had two less short consensus repeats. The porcine adhesion molecule could also support the adhesion of both porcine and human neutrophils. Expression of E-selectin on interleukin-1α (IL-1α)- or tumour necrosis factor-a (TNF-α)-activated porcine aortic endothelial cells in culture was prolonged, persisting for up to 48 hr. Binding studies using a chimeric molecule consisting of the lectin domain of porcine E-selectin and the epidermal growth factor (EGF) domain of human E-selectin fused to the human IgG constant region, further characterized porcine E-selectin as recognizing mainly granulocytic leucocytes and a subpopulation of lymphocytes. [ABSTRACT FROM AUTHOR]

We have developed a novel subcutaneous sponge matrix model in major histocompatibility complex (MHC) homozygous SLAb/b inbred pigs to study lymphocyte-endothelial cell interactions during inflammation. Polyether sponges were implanted subcutaneously and left for 12 days before injection of proinflammatory agonists. Implanted sponges became highly vascularized and showed markedly increased uptake of i.v.-injected 51Crk-labelled lymphocytes S hr after injection of turnout necrosis factor-α (TNF-α) (3000 U) or phytohaemagglutinin (PHA) (37 µg). Lower levels of traffic were seen in sponges S hr after injection with interleukin-1α (IL-1α) (3000 U) and no significant traffic occurred in sponges injected with phorbol 12-myristate 13 acetate (PMA) (15 ng) at 5 hr or PHA at 24 hr (compared to sponges injected with medium alone). Electron microscopy of control sponges revealed low numbers of infiltrating leucocytes and relatively 'flat' endothelium. Many more infiltrating leucocytes were present in PHA-injected sponges. However, no ultrastructural evidence was seen of any significant difference between control and activated endothelium. Immunocytochemistry of frozen sections from sponges showed that E-selectin expression was up-regulated markedly by TNF-α and PHA at 5 hr, only moderately by IL-1α, at 5 hr, and not at all by PMA at 5 hr. By 24 hr in PHA-injected sponges Eselectin expression had fallen markedly from the level seen at 5 hr. Flow cytometric analysis of cellular infiltrates dispersed from sponges injected with TNF-α, PHA, IL-1α or medium alone, revealed differences in lymphocyte subset populations. The infiltrate in sponges injected with TNF-α 5 hr before removal was dominated by high numbers of CD2+ lymphocytes, whereas the infiltrate induced by PHA showed relatively higher levels of CD2- CD4- CD8- γδ T-cell receptor+ (TCR+) T cells revealed by population-specific monoclonal antibodies (mAb). This model, which permits harvesting of leucocytes and endothelial cells for manipulation in vitro, will be useful for the study of leucocyte-endothelial cell interactions in subacute and chronic inflammation. [ABSTRACT FROM AUTHOR]

In vitro adhesion assays were used to directly compare the adhesion o f polymorphonuclear leucocytes (PMN) and T cells to endothelial cells (EC). PMN exhibited lower binding to unstimulated EC than T cells. When EC were stimulated with interleukin-1 (IL-l ), tumour necrosis factor (TNF) or bacterial lipopolysaccharide (LPS) there was a large and rapid increase in adhesiveness for PMN which peaked at 4 hr, This had fallen significantly by 24 hr and by 72 hr was not significantly elevated above unstimulated adhesion. The increase in adhesiveness of cytokine-stimulated EC for T cells was smaller and more gradual than for PMN, with adhesion peaking around 8 hr and remaining significantly elevated at 72 hr. In contrast, interferon-gamma (IFN-γ) enhanced EC adhesiveness for T cells but not for PMN, with maximal T cell EC adhesiveness occurring 24 hr after stimulation. As leucocyte adhesion Io vascular endothelium is the first step in diapedesis, differences in PMN and T-cell adhesion to EC may be important in determining the timing and composition of inflammatory infiltrates. [ABSTRACT FROM AUTHOR]