Chemotactic Factor Inactivator Activity Research Articles

Functional Loss of Chemotactic Factor Inactivator in the Adult Respiratory Distress Syndrome

The adult respiratory distress syndrome (ARDS) is often characterized by a neutrophilic alveolitis, which may be mediated in part by the neutrophil chemoattractant, C5a. Chemotactic factor inactivator (CFI) can decrease C5a-directed neutrophil chemotaxis. Thus, a loss of CFI activity in the ARDS lung could lead to an increased ability of C5a to attract neutrophils. Lung CFI levels were measured antigenically and functionally in bronchoalveolar lavage (BAL) fluid obtained from 29 patients with ARDS and in 14 normal control subjects. Antigenic levels of CFI were found to be markedly elevated in ARDS BAL fluid (1,855 +/- 437 ng/ml) compared with that in normal BAL (29 +/- 10 ng/ml, p less than 0.005), but, in contrast, CFI functional activity was markedly decreased in ARDS BAL fluid compared with that in normal BAL fluid (31 +/- 7% inhibition versus 76 +/- 5% inhibition, p less than 0.01). Furthermore, although purified CFI readily inhibited the ability of C5a to attract neutrophils (92% inhibition), this activity was decreased when BAL fluid from patients with ARDS was incubated with CFI (47 +/- 10%, p less than 0.01). These findings suggest that patients with ARDS are functionally deficient in CFI, leading to an increased ability of C5a to attract neutrophils.

Development of chemotactic factor inactivation - a fetal lamb model.

Summary: To study the developmental pattern of chemotactic factor in-activator (CFI) activity, although avoiding the effects of labor and delivery, serial blood samples were obtained from eight chronically catheterized lamb fetuses, 13 pregnant, and 13 nonpregnant ewes. The biologic profiles of adult sheep neutrophils in response to sheep C5-derived chemotactic fractions (C5-fr) were determined by the chemotactic and lysosomal enzyme release assays. CFI activity in sheep plasma was characterized and measured by the % inhibition of C5-fr-induced neutrophil lysosomal enzyme release. The chemotactic and enzyme release profiles of sheep neutrophils paralleled those of human neutrophils. Sheep plasma was shown to contain a CFI-like activity similar to that in human plasma. Mean CFI activity was higher in the plasma of pregnant ewes as compare to nonpregnant ewes (7.60 versus 5.15%, P < 0.001). Higher CFI levels (39.5%) were shown in the plasma of chronically catheterized fetuses early in the third trimester of pregnancy (109 days gestational age). These fetal levels decreased progressively to attain normal adult levels at fetal maturity (147 days gestational age) and no significant changes were noted at or after birth. Because identical changes occurred in all chronically catheterized fetuses, a developmental pattern was defined for CFI. Control CFI levels from six acutely catheterized fetuses did not differ from those predicted by the developmental pattern. Thus, the changes in CFI activity were not related to the chronic catheterization or to events surrounding labor and delivery; rather CFI levels correlated best with fetal immaturity. CFI levels correlated inversely with ability of zymosan activated plasma to induce neutrophil chemotaxis (r = —0.96, P < 0.01), suggesting that CFI plays a major role in the regulation of leukocytes chemotaxis. These data confirm previous findings in human neonates and provide a model for future studies. Further studies into the biology of the changes in CFI activity in the fetus and the influence of such high risk factors as prematurity, fetal distress or premature rupture of membranes should enhance our understanding of the immunocompromised neonate.

Elevation of serum chemotactic factor inactivator activity during acute inflammatory reactions in patients with hypersensitivity pneumonitis.

Inflammatory mediators such as the vasoactive and chemotactic factors derived from the activation of the complement system are extremely potent biological peptides that are under rigid control of specific serum-derived regulators, e.g., the anaphylatoxin inactivator (AI) and the chemotactic factor inactivator (CFI). We have previously demonstrated that serum chemotactic factor inactivator concentrations are altered during chronic inflammatory states; here we demonstrate that a rapid elevation of serum CFI activity occurs during acute inflammatory reactions in patients suffering from hypersensitivity pneumonitis. Specifically, serum CFI concentrations were evaluated in patients with hypersensitivity pneumonitis (pigeon breeder's disease) and control subjects (asymptomatic) after aerosol challenge with 2 ml of sterile pigeon serum. At 4 h postchallenge, serum CFI concentrations in the patients with hypersensitivity pneumonitis increased rapidly to 3 times the prechallenge serum concentrations. Asymptomatic (control) subjects showed no increase in serum CFI concentrations after exposure to pigeon serum. In independent studies, we have also demonstrated that serum CFI concentrations are elevated in (1) rabbits with glycogen-induced peritonitis, (2) rabbits after intravenous infusion of C5-derived chemotactic factors, and (3) patients undergoing hemodialysis. These combined data clearly demonstrate that serum CFI activity is rapidly elevated during acute inflammatory reactions within both patient and animal populations, and suggest that serum CFI may represent a "hyperacute" phase reactant that is elevated during inflammation. Possibly, this elevation of CFI may be induced in response to inflammatory mediators produced during inflammation. Thus, the acute elevation of serum CFI concentrations that occurs during acute inflammation may represent the control system that would be responsive to the regulatory needs of the body during inflammatory reactions.

Cell-directed inhibitor of human leukocyte locomotion. Identification of immunoglobulin G as a cell-directed inhibitor in normal human serum.

Abstract We purified a CDI of leukocyte locomotion from normal human serum and identified it as IgG. We studied the effect of purified whole IgG, its Fc and Fab fragments, IgA, and IgM on leukocyte locomotion in micropore filters, using measurements of both the distance migrated and the number of cells migrating (mass migration). Based on the distance migrated by the fastest PMNLs, the %I max is 40% ± 13 (mean ± S.D.) for IgG, 46% for the Fc fragment, and 40% for IgA. The inhibitor concentrations producing half-maximal inhibition (K i ) are 0.083 ± 0.053 μM for IgG, 2.4 for the Fc fragment, and 0.042 for IgA. Based on the number of granulocytes migrating into the filters (mass migration response), %I max is 50% ± 10 for IgG, 88% for the Fc fragment, and 72% for IgA. The K i values are 0.051 ± 0.036 μM for IgG, 4.2 for the Fc fragment, and 0.12 for IgA. No effect was observed with the Fab fragment up to a concentration of 33 μM or with IgM up to a concentration of 1.5 μM. The inhibition produced by IgG in the upper compartment of the modified Boyden chamber was not affected by the presence of chemotactic attractant in the lower compartment, indicating that it is an inhibitor of locomotion rather than of the chemotactic response per se and that the observed inhibitory effect of IgG on chemotaxis is actually the result of its effect on locomotion. When IgG was present in the lower compartment with chemotactic factors, neither inhibition nor stimulation was observed. Thus IgG possesses neither chemotactic factor inactivator activity nor chemotactic activity. Consistent with the other previously noted effects of CDI, IgG also inhibits the locomotion of monocytes and decreases the phagocytic responses of both PMNLs and monocytes. Finally, IgG also increases the adherence of neutrophils to nylon fibers. These results indicate that in addition to its other known activities, IgG may be an important regulator of PMNL function. (J Lab Clin Med 98:58, 1981.)

Interrelationships between Serum Chemotactic Factor Inactivator, Alpha1-Antitrypsin Deficiency, and Chronic Obstructive Lung Disease1–4

Serum chemotactic factor inactivator (CFI) activity was quantitated in 22 subjects with chronic airflow obstruction (CAO); 8 had normal antitrypsin levels (Pi M phenotype), 6 had intermediate antitrypsin deficiency (Pi MZ phenotype), and 8 had severe antitrypsin deficiency (Pi Z phenotype). We studied 19 healthy subjects with normal lung function as controls; 3 had Pi M and 6 had Pi MZ phenotypes. Subjects with CAO, irrespective of the alpha 1-antitrypsin (AAT) phenotype, had significantly lower CFI activity than the normal subjects; the lowest levels were found in those with CAO and Pi Z phenotype. Normal subjects with intermediate AAT deficiency and MZ phenotype had normal levels of CFI. The results suggest that deficiency of serum CFI may be important in the pathogenesis of chronic airflow obstruction, particularly in those with severe AAT deficiency.

Chemotactic factor inactivator release from rat leukocytes.

Rat neutrophils, alveolar macrophages, and peritoneal macrophages each released chemotactic factor inactivator (CFI) activities under conditions of endocytosis (uptake of opsonized zymosan particles and preformed immune complexes). CFI activities in supernatant fluids from phagocytizing leukocytes were found for the chemotactic factors from the third (C3) and the fifth (C5) components of complement and for the bacterial chemotactic factor (present in culture supernatant fluids from Escherichia coli.) CFI activity could also be demonstrated in homogenates obtained from disrupted leukocytes. CFI release from intact leukocytes was dependent on the duration of incubation of leukocytes with the phagocytic stimulus. No quantitative relationships were noted between the amount of CFI activity and the amount of beta-glucuronidase in phagocytic supernatant fluids released from leukocytes. The release of CFI activities from phagocytizing leukocytes may represent a regulatory ("turn-off") mechanism for the inflammatory response.

Characterization of the protease activity in the chemotactic factor inactivator.

The chemotactic factor inactivator (CFI) isolated from human serum contains a kininase activity that causes extensive hydrolysis of bradykinin. The highly chemotactic synthetic peptide Met-Leu-Phe was completely hydrolyzed by CFI preparations. The release of the constituent amino acids from this peptide coincided with a loss of its chemotactic activity. The N-formyl, but not the amide derivative, of the leukotactic peptide Met-Leu-Phe was resistant to the action of CFI, as evidenced by chemotactic and biochemical assays. Examination of the specificity of CFI proteolysis revealed that short polypeptide substrates are degraded sequentially from the amino terminus. Larger peptides are less extensively hydrolyzed, and the patterns of hydrolysis are more complex. Inactivation of the bacterial chemotactic factors by CFI was overcome by the addition of high concentrations of peptides which were substrated for CFI. CFI preparations readily hydrolyzed the peptide Arg-Phe-Ala. The constituent amino acids were conveniently identified by thin-layer chromatography method. This procedure afforded a rapid assay for measuring CFI activity in the whole human serum as well as in fractions throughout the purification steps. Moreover, CFI also hydrolyzed L-leucyl-beta-napthylamide at rates comparable to peptides. Thus, L-leucyl-beta-napthylamide served as a useful substrate for estimating CFI activity in preparations at various stages of purification. This substrate was also useful in kinetic studies. The results from these studies indicate an aminopeptidase activity is the mechanism whereby CFI inhibits the activity of chemotactic substrates.

Antileukotactic properties of tumor cells.

A chemotactic factor inactivator (CFI) has been found in extracts of Walker and Novikoff tumor cells maintained in rats. The CFI directly inactivates the bacterial chemotactic factor as well as the leukotactic activity (fro both neutrophils and monocytes) associated with C3 and C5 fragments and with culture fluids of lectin-stimulated lymphoid cells. The inactivation of the bacterial chemotactic factor is temperature and pH dependent. Subcellular fractionation procedures indicate that CFI is largely associated with the microsomal and cytosol fractions of tumor cells. CFI activity is also found in rat neutrophils, alveolar macrophages, and in extracts of liver, spleen, and kidney from normal animals. CFI derived from normal tissues also directly inactivates the bacterial chemotactic factor and has the ability to inactivate chemotactic activity associated with C3 and C5 fragments. A feature of the tumor-associated CFI is its presence in ascitic fluids of animals bearing tumor cells and the relative absence of any CFI activity in acute inflammatory exudates. The finding of the tumor-associated CFI may explain, at least in part, the tendency of malignant tumor cells to suppress cellular inflammatory reactions.