A new assay for leukocyte chemotaxis using cell retrieval, electronic particle counting and flow cytometry

Reduced immune responses to an aseptic inflammation in mice with congestive heart failure

We previously found that mice with congestive heart failure (CHF) were anemic, had decreased bone marrow haematopoiesis and functionally impaired neutrophilic granulocytes despite normal blood concentrations of these cells. We now asked if CHF-mice could mount an adequate immune response when challenged with an acute inflammation. A postinfarction heart failure was induced in mice. Six weeks later the mice had developed CHF. At that time a sterile peritonitis was induced by injection of a casein digest. Five hours after this injection a marked neutrophilia had developed. Specimens were then obtained from peritoneal washings, bone marrow and blood. Total bone marrow cell numbers were halved in CHF-peritonitis mice compared with sham-peritonitis mice. Bone marrow colony-forming cell numbers in CHF-peritonitis mice were only 14% of those in sham-peritonitis mice. The mobilization of leucocytes to the blood was much lower in CHF-peritonitis mice than in sham-peritonitis mice (5.6 vs. 8.1 million cells/mL), as was the peritoneal influx of these cells (1.6 vs. 4.1 million cells). A profound decline (>50%) in the functional activity, determined with various in vitro assays, was evident for both neutrophilic granulocytes and lymphocytes from CHF-peritonitis mice. Heart failure after myocardial infarction in mice may severely compromise their ability to combat an inflammatory challenge.

Preserved granulocyte formation and function, as well as bone marrow innervation, in subjects with complete spinal cord injury

Patients with a spinal cord injury are at risk of infections and is partly attributed to immobilization. Their lymphocyte-mediated immunity is impaired and the growth of blood progenitor cells is reduced. An adequate immune response depends on granulocytes being mobilized rapidly and activated properly, at the inflammatory site. Possibly this requires a coordinated interaction between the autonomous nervous system and cells within the haematopoietic bone marrow. Granulocyte function in the spinal cord injured has not been evaluated. Although there is evidence that the bone marrow in rodents is innervated, it is uncertain whether human bone marrow is similarly affected. Microscopy and immunolabelling followed by flow cytometry, showed that blood and bone marrow counts of leucocyte subsets were similar in paraplegic, tetraplegic and control subjects (P > 0.05). Neutrophilic migration and oxygen consumption, as well as eosinophil activation, assayed as release of eosinophilic cationic protein or CD69 expression, were not altered after spinal cord injury (P > 0.05). Cryostat sections of human bone marrow biopsies stained positive with glyoxylic acid, indicating the presence of catecholamine-containing nerves in both the patients and the controls. We conclude that terminal differentiation and formation of granulocytes, as well as their functional capacity, do not depend appreciably on supraspinal nervous regulation.

Delayed leukocytosis after hard strength and endurance exercise: aspects of regulatory mechanisms

Background

During infections, polymorphonuclear neutrophilic granulocytes (PMN) are mobilized from their bone marrow stores, travel with blood to the affected tissue, and kill invading microbes there. The signal(s) from the inflammatory site to the marrow are unknown, even though a number of humoral factors that can mobilize PMN, are well known. We have employed a standardized, non-infectious human model to elucidate relevant PMN mobilizers. Well-trained athletes performed a 60-min strenuous strength workout of leg muscles. Blood samples were drawn before, during and just after exercise, and then repeatedly during the following day. Cortisol, GH, ACTH, complement factors, high-sensitive CRP (muCRP), IL-6, G-CSF, IL-8 (CXCL8) and MIP-1β (CCL4) were measured in blood samples. PMN chemotaxins in test plasma was assessed with a micropore membrane technique.

Results

About 5 hr after the workout, blood granulocytosis peaked to about 150% of baseline. Plasma levels of GH increased significantly 30 min into and 5 min after the exercise, but no increase was recorded for the other hormones. No significant correlation was found between concentrations of stress hormones and the subjects' later occurring PMN increases above their individual baselines. Plasma G-CSF increased significantly – but within the normal range – 65 min after the workout. IL-6 increased very slightly within the normal range, and the chemokines IL-8 and MIP-1β did not increase consistently. However, we found a significant increase of hitherto non-identified PMN-chemotactic activity in plasma 35, 50, and 60 min after the exercise. No systemic complement activation was detected, and (mu)CRP was within the reference range at rest, 5 h and 23 h after the exercise. After endurance exercise, similar findings were made, except for a cortisol response, especially from non-elite runners.

Conclusion

Apparently, a multitude of humoral factors can – directly or indirectly – mobilize PMN from marrow to blood; some of the factors are, others are not known to be, chemotactic. Under different conditions, different selections of these mobilizers may be used. In the late granulocytosis after heavy, long-lasting exercise a number of factors thought capable of mimicking the granulocytosis of infectious diseases were apparently irrelevant.

Development and comparison of in vivo and in vitro models for endometritis in cows and mares

In order to investigate pathogenic mechanisms of acute endometritis in cows and mares, we established an in vivo model in both species. Based on the results of an in vitro transmigration system, human recombinant interleukin-8 (rhIL-8; 1.25 microg per mare and 5 microg per cow in 50 ml phosphate-buffered saline) was used to attract polymorphonuclear neutrophil granulocytes (PMNs) into the uteri. Peak numbers of uterine neutrophils were attracted after 6h, in both cows and mares. On average, mares responded more sensitively than cows, with 15 times higher numbers of rhIL-8-attracted uterine neutrophils (72+/-8 x 10(7)cells). In contrast to in vitro studies, in vivo migrated neutrophils (uterine neutrophils) of both species displayed a significantly reduced MHC class I expression. Expression of the CD11a molecule was significantly enhanced on equine uterine neutrophils but downregulated on bovine cells. Compared with untreated autologous peripheral neutrophils, both uterine and in vitro migrated neutrophils showed no alteration of phagocytic capacity. The ability to generate reactive oxygen species (ROS) was significantly upregulated in bovine and equine uterine neutrophils. This was also observed after in vitro migration of equine neutrophils, whereas ROS generation by bovine neutrophils was significantly depressed. In summary, the concept of inducing endometritis directly by local application of human interleukin-8 has been reliably successful in cows and mares. The model permits the analysis of PMN migration into the uterus under defined and controlled conditions. The observed differences between cows and mares with respect to phenotypical and functional characteristics of in vivo attracted uterine cells point to species-related features of neutrophil migration. In vitro transmigrated bovine and equine cells partially differ in phenotype and function from uterine neutrophils. Therefore, the in vitro transmigration assay cannot completely represent the in vivo endometritis model described here.

Modulation by interferons of human neutrophilic granulocyte migration

The effect of various interferons (IFN) on neutrophilic granulocyte (PMN) random and directed migration is incompletely understood. We, therefore, investigated PMN migration with a novel micropore membrane technique. No chemotactic effect of either 10-10000 U/ml IFN-alpha or IFN-beta, or 1-1000 U/ml IFN-gamma was observed on PMN isolated from normal human venous blood. However, when present on both sides of the micropore membrane, all the IFN (1000 U/ml IFN-alpha and IFN-beta, 100 U/ml IFN-gamma) inhibited both random and directed migration toward zymosan-activated serum (ZAS). IFN-gamma was the most potent inhibitory agent and produced an inhibition of about 30%. When the bacterial peptide fMLP was used as a chemoattractant, IFN-gamma also depressed chemotaxis. Taking the reduced random migration of IFN-gamma treated cells into account, however, chemotaxis per se-toward both ZAS and fMLP-was not significantly affected. Random migration and directed migration assessed simultaneously with PMN from the same donor were clearly correlated for both control and IFN-gamma treated cells, suggesting that a general antimotility effect of IFN-gamma might explain both reduced random migration and chemotaxis. The antimotility effect of IFN-gamma was not dependent on protein synthesis or on tyrosine kinase activity. In fact, inhibition of tyrosine kinase with herbimycin A increased the ZAS-stimulated motility of both control and IFN-gamma-inhibited PMN. In conclusion, our data indicate that IFN depress both random and directed PMN migration by mechanisms that do not involve protein synthesis or protein tyrosine kinase activity.

Simultaneous assessment of migration and proliferation of murine fibrosarcoma cells, as affected by hydroxyurea, vinblastine, cytochalasin B, Razoxane and interferon

Using porous cell culture chambers, we have simultaneously assessed growth and locomotion of cancer cells to investigate whether certain agents affect cell motility in addition to cell division. First, cells from a murine fibrosarcoma cell line, 1.0/L1, were grown in ordinary flask cultures to determine appropriate cell inocula. Doses of agents were selected to reduce the final 4 day culture cellularity to about 50%, when present during the last two days of culturing. Secondly, the effects of these agents on cell numbers in the porous chambers and on cell migration out of the chambers ('emigration fraction') were recorded. We also examined, using a similar type of porous chamber, whether the agents could affect leucocyte chemotaxis. Hydroxyurea (an inhibitor of DNA synthesis) reduced cancer cell emigration as well as cell growth, without interfering with leucocyte chemotaxis. Cytochalasin B (a microfilament disrupting agent) inhibited cancer cell motility and growth, as well as leucocyte chemotaxis. Vinblastine (a microtubule disrupting agent), at the very low dose chosen, reduced cancer cell growth, but did not consistently affect the migration of either cell type. The experimental anti-metastasis agent Razoxane reduced growth, but had no detectable effects on motility. High doses of natural murine interferon-alpha/beta weakly inhibited both cancer cell growth and locomotion. This motivates for further studies of these and other cytokines, as treatment with agents inhibiting cancer cell locomotion might possibly prevent peri-operative spread of cancer in patients.

Growth and metastasis of hypermotile, hyperinvasive cancer cells selected in vitro by rapid locomotion under various conditions

Cancer cells selected from a cultured murine fibrosarcoma by rapid migration through micropore membranes moved considerably faster through such membranes and invaded biological tissues much more efficiently than did the unselected parent cells. The present data show that populations of cells selected by unstimulated migration or by haptotaxis to laminin moved not only faster, but also in larger numbers than the parent cells. However, the selected cells were far less efficient than the parent cells in forming spontaneous lung metastases in syngeneic mice, although all cell lines were 100 per cent tumorigenic. Analysis of paired data within each group showed no relationship between the primary tumor size at any observation time and the number of lung metastases finally formed. Therefore, although the parent cell line produced primary tumors growing slightly more rapidly than did the various lines of hypermotile cells, this was probably not the main cause of the difference in spontaneous metastasis formation between the groups. Lung colonization experiments performed by intravenous injection of cells could not explain the spontaneous metastasis results. In vitro, the cells selected by rapid haptotaxis to laminin grew considerably better than the other cells in 0.1 per cent fetal bovine serum, but there were no, or only minor, differences in higher serum concentrations. Combined, these results indicate that small subpopulations of cells selected by extreme efficiency in one step of the metastasis process may be so specialized that they perform poorly in other steps. Therefore, the results do not disprove the concept that tumor cell migration plays an important part in metastasis.

Direct evidence that cancer cell locomotion contributes importantly to invasion

This study was undertaken to clarify whether active locomotion of cancer cells is important for their ability to invade. The most rapidly moving cells were isolated from a cultured murine parent fibrosarcoma by successive cycles of migration through a micropore membrane. Cells were isolated by unstimulated locomotion and by haptotaxis to laminin, and the selected cells did indeed constitute rapidly locomoting subpopulations. These cells invaded biological tissues more efficiently than did the unselected parent cells. The cells selected by haptotaxis to laminin invaded most rapidly through amnion with basement membranes (containing laminin). Cancer cell haptotaxis to laminin in basement membranes thus promotes penetration of these tissue barriers. These results show in a direct manner that cancer cell locomotion is in fact important in invasion of biological tissues.

A new in vitro assay for cell motility and proliferation

We have described and characterized a new micropore membrane assay for migration and proliferation of cells of various tumourigenic potential. The assay was developed to facilitate analysis of some aspects of cancer invasion and metastasis. Tumorigenic and non-tumorigenic C3H/10 T 1/2 cells grow in and migrate out of a culture chamber during a 1-11 day period, the shorter periods are used for chambers with 6 micron thick polycarbonate membranes, the longer ones for 140 micron thick cellulose nitrate membranes. Cell growth within the chambers, in their micropore membranes and on the outside of the membranes, was assessed with microscopy, electronic cell counting, flow cytometry of propidium iodide (PI) stained cells, and 3H-thymidine [( 3H]TdR) incorporation. A complete retrieval of intact cells that have traversed the membraneous chamber wall is possible, and these cells can be recultured or used in other studies. The tumorigenic cells had a steeper growth curve in vitro than the non transformed cells, but the relative sizes of the emigrated subpopulations were not significantly different. The subpopulation of tumorigenic cells that emigrated spontaneously from the chambers was less able than the subpopulation retained to populate secondary chamber cultures, suggesting that the clonogenic (stem) tumour cells are 'slow movers'.

Multiwell cap assay: a simple objective method for the assessment of leukocyte locomotion in vitro

A simple method for evaluating leukocyte locomotion in vitro has been developed and validated for several chemoattractants. The multiwell cap assay (MWCA) comprises chambers constructed from readily available disposable plastics and is quickly assembled, permitting large experimental protocols. Leukocytes which have migrated through a micropore filter are recovered and counted electronically yielding a precise, objective result. Coefficients of variation are approximately 6%.

Membrane associated events during proliferative inhibition of granulocyte precursors

A new way of assessing the significance of intracellular signals that may regulate cellular proliferation, would be to analyze possible 'second messengers' when proliferation is slowed down, rather than stimulated. Therefore, we examined proliferating mononuclear blood cells from leukaemic patients which had been exposed to an inhibitory ox leucocyte extract. The extract decreased 3H-thymidine incorporation in leukaemic cells in short-term cultures. The inhibition was not cell-line specific, but was nevertheless non-toxic and not due to endotoxin. The K+ flux into the leukaemic cells was assessed with 86Rb+, a K+ analogue. An inverse relationship was found between 86Rb+ uptake and 3H-thymidine incorporation. The increased 86Rb+ influx was probably due to leakage or exchange mechanisms other than the Na+/K+ membrane pump, as suggested by ouabain inhibition experiments. However, the long lag time (greater than 45 min) between addition of inhibitor and a marked increase in 86Rb+ uptake does not support a role for the K+ flux as an early mediator of the inhibitory signal.

A new method for rapid technetium-99m labelling of leucocytes: functional cell studies in vitro

The aim of this study was to assess the cytotoxicity of a new leucocyte-labelling method, which may be used clinically to localize inflammatory and immune reactions. Human blood leucocytes, their mononuclear sub-population, and mouse mononuclear bone marrow cells were labelled with 99mTc for 30-45 min, washed once, and then evaluated in various functional assays. The new procedure includes [99mTc]-labelling with a bisalt method, in the presence of dihydroxybenzoic acid as an intermediate antioxidant-complexing stabilizer, and a carboxylic acid salt of stannous ions as a reducing agent. To challenge the method, cells were labelled about two orders of magnitude more heavily in these initial methodological studies than in on-going clinical trials. Labelled leucocytes ingested latex beads as readily as the controls, but migrated chemotactically and randomly somewhat slower than the control cells. The lymphocytes were triggered by PHA and Con A in a normal way. However, lymphocytes and haemopoietic progenitor cells exposed to radiation for several days, were killed by the isotope doses used, of which about 2% (i.e. 20 MBq) were bound per million cells. All deleterious effects were apparently due to irradiation, and the labelling procedure itself did not damage the cells.