Recombinant human tumor necrosis factor (TNF) was found to enhance the adherence of human peripheral blood neutrophils to human umbilical vein endothelial (HUVE) cell monolayers in vitro. The enhancement was due to the effects both on neutrophils and HUVE cells. The effect on neutrophils was maximally induced within 5 min and did not require protein or RNA synthesis. By contrast, maximal effects on HUVE cells took 4 hr to develop and required de novo protein and RNA synthesis; however, exposure of HUVE cells to TNF for as little as 5 min was sufficient to initiate changes leading to maximal adherence of neutrophils at 4 hr. Both the effect on neutrophils and that on HUVE cells were blocked by a monoclonal antibody against TNF. TNF also rapidly induced an increased surface expression of neutrophil antigens recognized by monoclonal antibodies directed against epitopes of a glycoprotein required for optimum adherence and for complement component C3bi receptor (CR3) function. Thus, the mechanism of action of TNF may involve the regulation of expression of cell surface molecules. Our observations show that TNF induces a process central to the development of all inflammatory reactions and that both blood neutrophils and endothelial cells are targets of TNF action. The regulation of inflammatory reactions by TNF or antagonists of TNF has wide-ranging clinical implications.

Stimulation of the adherence of neutrophils to umbilical vein endothelium by human recombinant tumor necrosis factor.

Structure and function of the leukocyte adhesion molecules CD11/CD18

A unique method is disclosed for identifying and replacing immunoglobulin surface amino acid residues which converts the antigenicity of a first mammalian species to that of a second mammalian species. The method will simultaneously change immunogenicity and strictly preserve ligind binding properties. The judicious replacement of exterior amino acid residues has no effect on the ligind binding properties but greatly alters immunogenicity.

Method for reducing the immunogenicity of antibody variable domains

Recent studies indicate that polymorphonuclear neutrophils (PMNs) infiltrate the intestinal mucosa during ischemia and after reperfusion. To determine whether PMNs mediate the increased microvascular permeability produced by ischemia-reperfusion (I/R) we treated cats with either saline, antineutrophil serum (ANS), or a monoclonal antibody specific for the beta-chain of the CD18 complex (MoAb 60.3) that prevents neutrophil adherence and extravasation. Intestinal microvascular permeability to plasma proteins was measured in control preparations (0.08 +/- 0.007), in preparations subjected to 1 h of ischemia then reperfusion (I/R, 0.32 +/- 0.02), I/R preparations treated with ANS (0.13 +/- 0.01), and I/R preparations treated with MoAb (0.12 +/- 0.003). Our results indicate that both PMN depletion (to less than 10% control) and prevention of PMN adherence significantly attenuate the increased microvascular permeability induced by I/R. These findings, coupled to previous results obtained from this model, support the hypothesis that neutrophils, which accumulate in the mucosa in response to xanthine oxidase activation, mediate the oxyradical-dependent injury produced by reperfusion of the ischemic bowel.

Role of neutrophils in ischemia-reperfusion-induced microvascular injury

Cell communication is essential to development, tissue organization and function of all multicellular organisms. Cells communicate with each other and with their environment via soluble mediators and during direct contact. In the immune system leukocytes are involved in a host of cell-soluble mediator, cell-cell and cell-matrix interactions. For instance, an acute inflammatory response is initiated by release of soluble substances at the site of injury that direct leukocyte migration and localization. The circulating leukocytes arriving at the site of injury must directly adhere to the endothelium and basement membrane during extravasation from the circulation. Once in the tissue, leukocytes will migrate in response to gradients of chemoattractants and to adhesive gradients. The leukocytes will adhere and de-adhere to a variety of cells, finally find infected or antigen-presenting cells, adhere to them and deliver the appropriate immunological response. Discovery of several cell surface receptors involved in cell-cell, cell-substrate, or cell-soluble ligand binding has been a key factor in understanding the mechanisms underlying inflammatory and immune phenomena. Three protein families, the immunoglobulin (Ig) family (Williams & Barclay 1988, Williams 1987), the integrin family (Springer 1990, Kishimoto et al. 1989a, Hynes 1987, Ruoslahti & Pierschbacher 1987, Hemler 1988), and the recently designated selectin family (Tedder et al. 1989, Stoolman 1989, Springer 1990), have been described that are extensively involved in a network of cell-cell and cell-matrix interactions in the immune system. Engagement of these surface receptors can transduce a signal leading to cellular events that change the phenotype, movement, gene expression, or activation state of the cell. On the other hand, cytoplasmic signals regulate the functional activity and surface expression of these receptors. These receptors thus mediate a dialogue, transferring information in

Structure and function of leukocyte integrins.

We have described a monoclonal antibody, designated 603, which reacts with a cell surface antigen expressed by most peripheral blood and bone marrow leukocytes Immunoprecipitation showed at least three major components with relative mw of 95,000, 130,000, and 150,000 under reducing conditions Antibody 603 inhibited several cell-mediated immune functions The lytic activity of both cytotoxic T cells and natural killer cells was blocked in the presence of the antibody The proliferative responses of T cells stimulated by soluble antigens, mitogens, or allogeneic cells were inhibited when antibody 603 was added at the initiation of culture, but not when added after 48 hr Antibody 603 also blocked the migration of neutrophilic granulocytes The antigen identified by antibody 603 thus appears to be involved in a membrane-dependent cell activation pathway that is common to diverse functional systems and is shared by both lymphoid and myeloid cells

T H Price

Papers

Definition of a common leukocyte cell-surface antigen (Lp95-150) associated with diverse cell-mediated immune functions.