A possible role for cold insoluble globulin in chemotactic factor mediated polymorphonuclear leukocyte adherence to plastic

A Unique Monoclonal Antibody Against Human Plasma Fibronectin, Which Recognizes an Epitope on the Surface of a Subpopulation of Polymorphonuclear Neutrophils

A new monoclonal antibody (MAb) specific to plasma fibronectin, named MO, which was produced by immunizing a mouse with fragments of fibronectin isolated from human plasma, was found to bind to the surface of a subpopulation of peripheral blood polymorphonuclear neutrophils (PMNs) in the presence of physiological concentration of soluble fibronectin. MAb MO had no reactivity with other blood cells such as lymphocytes, monocytes, or platelets. The percentage of the MAb MO-reactive subpopulation of PMNs from healthy donors varied from 0 to 60%. Ten previously established MAbs against fibronectin tested in this study together with MAb MO had no reactivity with the surface of PMNs at all, when tested simultaneously with MAb MO. These results indicate that MAb MO can be a unique and useful tool for analyzing the structure and function of fibronectin-especially the fibronectin expressed on the surface of PMNs.

Endogenous fibronectin of blood polymorphonuclear leukocytes: immunochemical characterization and subcellular localization

Fibronectin, a large dimeric glycoprotein synthesized and secreted by several cell types, mediates cell adherence to surfaces. In infections and inflammatory responses, blood polymorphonuclear leukocytes (PMNs) adhere to cells and matrix proteins during extravasation and accumulation at inflammatory sites. The presence of fibronectin in blood PMNs has been poorly studied, and the characteristics and subcellular localization of this endogenous adhesive molecule are practically unknown. By immunofluorescence flow cytometry, purified rabbit antibodies and a monoclonal antibody to plasma fibronectin reacted with isolated blood PMNs, only after permeabilization of the cells. By Western blot analysis, the antibodies recognized, under reducing conditions, a protein with an apparent molecular mass of 230 kDa in the cell lysate. Eleven monoclonal antibodies to common frame fibronectin epitopes, including the RGD-containing cell-binding domain, also reacted with PMN fibronectin by Western blotting. In contrast, two antibodies to ED-A, the alternatively spliced region characteristic of "cellular" fibronectin, were unreactive, but recognized platelet fibronectin. On average, 1 million PMNs contained 6.8 ng +/- 1.4 (SD) of fibronectin, as measured by sandwich ELISA. Immunogold labeling and electron microscopy studies indicated localization of most fibronectin in PMN granules. Moreover, double-immunofluorescence and digital image analysis demonstrated colocalization of fibronectin with lactoferrin, a marker of specific (secondary) granules. The results indicate that blood PMNs contain approximately 8000 molecules per cell of intact ED-A-negative fibronectin localized mainly in their specific granules.

Fibronectin binding and neutrophil aggregation in burn injury

Fibronectin (Fn) plays an important role in the adhesive function of many cells including neutrophils (PMN). We examined the hypothesis that activated PMN develop binding sites for fibronectin which allows for the aggregation of contiguous PMN. Because PMN adhesive function is altered in acute burn injury, we also investigated the role of Fn in the aggregation of PMN from subjects with acute thermal injury. The chemotactic peptide, n-formylmethionyl leucyl phenylalanine, induced rapid binding of radioiodinated plasma Fn to PMN. Significant binding of Fn was detected as early as 30 sec poststimulus and maximal binding occurred at 5 min. Fn binding was only partially reversible and nonsaturable. The chemotactic peptide induced aggregation and binding of Fn to PMN with similar kinetics, concentration dependence, temperature, and cation requirements. In burn patients, PMN demonstrated a significant decrease in chemotactic peptide-induced aggregation which was associated with decreased binding of Fn. Alterations in the binding of Fn to PMN may be responsible, in part, for diminished aggregation responses of PMN in the early stages of thermal injury.

Enhancement of polymorphonuclear leukocyte-mediated tumor cytotoxicity by serum factor(s)

It has been reported that beta-1,3-D-glucan isolated from Alcaligenes faecalis (TAK) promoted tumor cytolysis by mouse polymorphonuclear leukocytes (PMN). We investigated the effect of serum on mouse PMN tumor cytolysis induced by TAK and other PMN stimulators. Addition of fetal calf serum (FCS) to the cytolysis assay enhanced tumor cytolysis by PMN in a dose-dependent manner. Sera obtained from horses, mice, and rats were also effective enhancers of PMN tumor cytolysis. When FCS was added after the assay was under way, the enhancing effect decreased proportionally to the time elapsed. The enhancing activity was detected over a broad range of fractions with a peak at 170 kD by fractionation on a Superose 6 column. The responsible factor(s) in serum was stable after treatment at 60 degrees C, 30 min or after lowering the pH to 2. Mouse PMN stimulated with TAK increased production of hydrogen peroxide in the presence of FCS.

Fibronectin is stored but not synthesized in mature human peripheral blood granulocytes

To investigate whether peripheral blood granulocytes can synthesize the adhesive glycoprotein, fibronectin, we sought to demonstrate the presence of messenger RNA coding for fibronectin within mature circulating granulocytes. Polyadenylated-enriched RNA was isolated from human peripheral blood granulocytes, human skin fibroblasts (synthesize fibronectin) and HeLa cells (lack fibronectin) and probed with a cDNA clone coding for the cell attachment domain of fibronectin. Hybridization of a fibronectin cDNA fragment occurred with fibroblast RNA but did not occur with granulocyte RNA despite a 100 fold excess granulocyte RNA. Incubation of granulocytes with n-formyl methionyl leucyl phenylalanine, a chemotactic peptide known to augment the release of fibronectin from granulocytes, failed to induce detectable levels of mRNA for fibronectin in granulocytes. There was no difference in the quantity of fibronectin released from chemotactic peptide-stimulated granulocytes pre-incubated in the presence or absence of the protein synthesis inhibitor, cycloheximide, suggesting that fibronectin exists in a stored form in granulocytes. These data suggest that fibronectin in mature granulocytes is the product of synthesis during early myeloid maturation.

Nutritional support of children with neoplastic diseases

There are numerous factors promoting the development of PEM in the child with cancer. Some of these factors are related to the tumor, many to the treatment itself, and some to failure of recognition of PEM. Not all children with cancer are at great risk for the development of PEM. These patients must be monitored and supported with comprehensive enteral programs. Children who have developed or are at risk for PEM must be identified and supported with CPN or PPN plus CEN during early intensive periods of treatment and during the later phases of abdominal radiotherapy, operative resection of tumor, or relapse. The decision to institute CPN must be based not only on the child's current nutritional status but also on the nature of the therapy he or she is soon to receive and the likelihood that he or she will be able to maintain an adequate intake during that therapy. Realistic goals must be set for nutritional support. The value of nutritional intervention lies in its ability to correct or prevent the development of adverse effects related to PEM. This support is hoped to contribute to improved tolerance of therapy, increased energy to complete normal day-to-day activities, and an improved sense of well-being for the child. If these goals have been accomplished, then the nutritional therapy has been successful.

Defective natural-killer- and killer-cell activity associated with increased polymorphonuclear leukocyte adherence in psoriasis

Patients (n = 45) with psoriasis vulgaris were studied for natural killer (NK) cell activity and antibody-dependent cell cytotoxicity (ADCC) of their peripheral blood mononuclear cells against K-562 and L1210 target cells, respectively. Simultaneously, the studies were performed on the adherence to human endothelium of polymorphonuclear leukocytes (PMN) from various forms of the disease. Mean values of NK-cell activity in psoriasis vulgaris, as a whole, and mean values of ADCC in male patients were significantly lower than in a group of healthy controls. This decrease was most pronounced in patients with the active form of the disease, in whom in vitro PMN adherence to human endothelium was found to be increased. Neutrophils from both patients with active psoriasis and healthy individuals were capable of reducing NK-cell activity of normal human mononuclear cells.

Fibronectin assays and their clinical application: a review

Cold insoluble globulin (fibronectin) was discovered 30 years ago but recently there has been a remarkable growth of knowledge concerning its interaction with the cell cytoskeleton and its role in cell-cell and cell-matrix adhesion. The protein is also a major plasma opsonin with a role in regulating fixed macrophage activity and it is this area in which clinical applications are now beginning to develop. Methods are discussed for measuring the concentration of the protein and its opsonic function in vitro, and for the evaluation of fixed macrophage function in vivo. Also discussed are the metabolism of the protein, the implications of opsonin depletion in patients with serious injury or infection and the attempts to reverse this with plasma protein replacement therapy.

Effect of fibronectin on adherence of neutrophils from newborn infants

Neutrophils (polymorphonuclear leukocytes [PMNs]) from infants and adults increased in adherence over a 20-min incubation as measured in a morphological assay. At each time point, PMNs from healthy infants had significantly diminished adherence when compared with those of adults; PMNs from sick newborn infants showed intermediate adherence values. Moreover, PMNs from healthy infants had significantly diminished membrane fluorescence for fibronectin when compared with those of adults. Preincubation with exogenous fibronectin did not augment the adherence of PMNs from infants or adults. Deficient adherence of PMNs from newborns may be related to decreased membrane fibronectin.

Concurrent estimation of the kinetics of adhesion and ingestion of Staphylococcus aureus by human polymorphonuclear leukocytes (PMNs)

Direct recording of the kinetics of early phagocytic events, recognition or adhesion and ingestion, may better characterize some forms of polymorphonuclear leukocyte (PMN) dysfunction. This report describes a method and criteria to discriminate concurrently between adhesion and ingestion of Staphylococcus aureus by human PMNs at the level of the light microscope. The criteria were confirmed by several lines of direct evidence: low temperature and cytochalasin b treatment of PMNs; lysostaphin digestion of target Staphylococcus aureus after PMN incubation; and differential ingestibility of colony types I and III N. gonorrheae. Concurrent determinations of the initial kinetics of adhesion and ingestion of bacteria by PMNs demonstrated generalized first order kinetics, sensitive to bacterial challenge ratio and total particle density. Most importantly, the method may be applied to determine if phagocytically defective PMNs actually fail to recognize opsonized bacteria.