Annexin V-coated intraocular lenses.

PURPOSE: To assess whether annexin V-coated poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) prevent postoperative inflammation in rabbit eyes. SETTING: Department of Ophthalmology, Hôpital Purpan, Toulouse, France. METHODS: Thirteen IOLs coated with annexin V were implanted in 13 rabbit eyes; the contralateral eyes received uncoated IOLs. Postoperative fibrin was quantitated by daily slitlamp examination until the anterior chamber was completely clear. Results were analyzed using a Wilcoxon test. Ocular toxicity was evaluated by light and electron microscopy. RESULTS: Eyes with the annexin V-coated IOLs had less severe inflammation on the first postoperative day, and the inflammation resolved more quickly than in eyes with uncoated IOLs (P < .05). No annexin V was released postoperatively, nor were there signs of ocular toxicity. CONCLUSION: Annexin V-coated lenses effectively reduced postoperative inflammation in rabbit eyes.

Low incidence of antibody formation due to long-term interferon-alpha 2c treatment of cancer patients.

In order to study the long-term immunogenicity of interferon-alpha 2c (Berofor) in cancer patients, serum was collected starting in 1983 from study patients with various proliferative diseases who received interferon-alpha 2c at different doses, according to different schedules, and via different routes. A total of 1992 samples were tested for the presence of anti-interferon-alpha 2c antibodies. Due to long-term interferon-alpha 2c treatment, 346 patients were eligible for induction of neutralizing anti-interferon antibodies over a treatment period of 2-52 months. Most patients were treated for longer than 6 months. Of the 346 patients, three patients (0.87%) exhibited measurable titers of neutralizing antibodies following therapy with interferon-alpha 2c. One hundred and sixty-three patients suffered from non-Hodgkin lymphomas, leukemias, and preleukemias. One patient with chronic myeloid leukemia experienced antibody induction under therapy. The other 183 patients had solid tumors. Two of them reacted with antibody production. All titers were very low (1:12, 1:8, and 1:64). Compared with figures reported for other interferon-alpha preparations, the propensity of interferon-alpha 2c to induce neutralizing antibodies seems to be very low. This property might be related to arginines occurring as critical residues in positions 23 and 34 of the interferon-alpha 2c molecule.

Highly sensitive enzyme immunoassays for antibodies to human tumor necrosis factor (TNF-alpha) and lymphotoxin (TNF-beta).

Two 'inverse sandwich' enzyme immunoassays (ELISAs) were developed for the detection and quantification of antibodies to human tumor necrosis factor (TNF-alpha) and lymphotoxin (TNF-beta), respectively. In these one-step assays, antibodies present in the sample linked antigen which had been covalently coupled to horseradish peroxidase to antigen bound to a solid phase (microtiter plates). The limits of detection of the assays were lower than those of neutralization bioassays; antibodies to TNF-alpha and TNF-beta being detected at concentrations as low as 2 ng/ml and 0.5 ng/ml, respectively, and no cross-reactivity was observed. The advantages of these ELISAs over other assay methods currently in use for the detection of antibodies include: (i) the convenience of the microtiter plate format and its suitability for testing large numbers of samples; (ii) the absence of radioactive tracers and precipitation steps; (iii) the high stability of the reagents; (iv) the avoidance of second antibodies and, thus, the possibility of testing samples from various species without modification of the assay and (v) the ability to detect low-affinity antibodies due to the absence of competitive reactions. The assays may be used without modification for the detection of antibodies in serum samples from both man and laboratory animals as well as in other samples such as hybridoma supernatants.

Highly sensitive enzyme immunoassay for human lymphotoxin (tumor necrosis factor beta) in serum.

We have developed a rapid, simple and highly sensitive 'sandwich' enzyme immunoassay (ELISA) for the detection and quantification of human lymphotoxin (= tumor necrosis factor beta) in serum. The assay, performed in microtiter plates, employs two monoclonal murine antibodies able to neutralize the cytotoxic activity of lymphotoxin. In a one-step procedure, antibody LTX-21 (IgG2b) coated on to the solid phase captures antigen present in the sample; subsequently antibody LTX-22 (IgG1), covalently coupled to horseradish peroxidase, labels the bound antigen. The assay is able to detect lymphotoxin spiked into human serum in concentrations as low as 7 pg/ml, whereas human tumor necrosis factor alpha does not cross-react even at 10(7)-fold higher concentrations. Only biologically active protein is recognized by the antibodies, since inactivation of lymphotoxin measured by bioassay results in a parallel decrease in immunoreactivity. Natural, glycosylated lymphotoxin shows the same reactivity as recombinant, unglycosylated protein. The assay will be useful for the quantification of endogenous human lymphotoxin in serum, other body fluids, and culture supernatants of human cells, and can also be used to monitor levels of recombinant human lymphotoxin in animal studies and clinical trials.

TNF- and LPS-induced changes of lung vascular permeability: studies in unanesthetised sheep.

There have been reports that the administration of TNF produces many of the cardiopulmonary changes seen with endotoxin (LPS). We asked whether all of LPS effects can be mimicked by TNF infusion. The effects of infusion of (human recombinant) TNF (50 micrograms/kg/30 min) and LPS (3 micrograms/kg/30 min) on permeability characteristics of sheep lungs were compared. Thirteen sheep were chronically instrumented for cardiopulmonary studies including lung lymph data. Infusion of LPS and TNF result in an increase of body temperature and lung lymph protein clearance (measured as the product of Lymph Flow and Lymph/Plasma Protein Ratio). The two responses had entirely different time courses. This might be related to the significantly longer period of pulmonary hypertension (MPAP) with LPS, which was only transient with TNF. Similar differences in plasma levels of thromboxane B2 (TxB2) were also noted. There were also differences in leukocyte kinetics, arterial blood gases, and plasma lactate levels. This indicates that although TNF infusion results in an increased pulmonary microvascular permeability, this event occurs without concomitant changes in thromboxane metabolism and exhibits time characteristics somewhat different from endotoxin.

Steroids decrease granulocyte membrane fluidity, while phorbol ester increases membrane fluidity. Studies using electron paramagnetic resonance.

High concentrations of corticosteroids inhibit granulocyte responses and disrupt agonist receptor function. Dose-response and time-course considerations make it unlikely that these effects are mediated via the glucocorticoid receptor, a concept further supported by the ability of sex steroids to work similar effects. We postulated that steroids nonspecifically altered granulocyte membrane fluidity, which we measured directly by electron paramagnetic resonance. As predicted, methylprednisolone caused a dose-dependent increase in order parameter (decrease in fluidity) calculated on the basis of EPR spectra, using 5-doxylstearic acid (5-DS) as a probe of resting PMN membranes. This trend was highly significant (P less than 0.001; P at 0.5 mg/ml less than 0.01). Qualitatively similar results (but with different dose-response features) were obtained with conjugated estrogen. Granulocyte agonists (such as PMA) showed an opposite effect, which was not oxidatively mediated and which was steroid-inhibitable. 16-DS showed less prominent effects, suggesting that the membrane leaflets were more strongly affected than was the deep region of the membrane. Ibuprofen, which has similar effects to those of methylprednisolone on PMN aggregation and receptor function, caused a fluidizing rather than a stiffening of the membrane; this surprising result may indicate that there is a critical range of membrane fluidity for normal function, outside of which--in either direction--agonist receptor dysfunction occurs. We conclude that the immediate effects of very high doses of steroids are probably not mediated by corticoid receptors; instead, they may be due to changes in membrane fluidity.

Tumour necrosis factor-alpha in infectious meningitis.

During a one year period tumour necrosis factor-alpha (TNF-alpha) was prospectively determined in the cerebrospinal fluid of 49 patients with infectious meningitis. TNF-alpha was found in the cerebrospinal fluid of 15 of 18 patients with bacterial meningitis. In 11 patients who had cerebrospinal fluid positive for TNF-alpha it was detected in only one serum (in low concentration). There was no significant correlation between the concentration of TNF-alpha in cerebrospinal fluid and the patient's age, duration of illness and fever, body temperature, and serum C reactive protein. However, cerebrospinal fluid protein concentrations of greater than or equal to 2 g/l and leucocyte values of greater than or equal to 2.5 X 10(9)/l were more often associated with high TNF-alpha concentrations (greater than or equal to 500 pg/ml). In contrast with bacterial meningitis, none of the 31 samples of cerebrospinal fluid from patients with viral meningitis was positive for TNF-alpha. Thus this investigation supports the conclusion, drawn from animal studies on TNF-alpha in the cerebrospinal fluid, that the presence of TNF-alpha is indicative of bacterial meningitis. Absence of TNF-alpha cerebrospinal fluid, however, was found here not to exclude a bacterial aetiology of the infection.

Development of a simple radioimmunoassay for human C3a.

A radioimmunoassay was devised for the human complement cleavage product, C3a, using charcoal separation and selective precipitation of interfering substances. When compared with the commercially available immunoassay now marketed, the assay reported here was somewhat simpler to perform; furthermore, it overcame delivery and availability problems in Europe. The assay showed a mean recovery of 87% of known amounts of C3a or C3adesarginine and had a sensitivity of 32 ng C3a per milliliter of plasma; coefficients of variance were comparable to other radioimmunoassays in common use. Using this assay in a first clinical application, we were able to document a small but statistically significant rise in [C3a] during cardiopulmonary bypass.

Inhibition of granulocyte function by steroids is not limited to corticoids. Studies with sex steroids.

Noting that corticosteroid doses required for protection in shock models exceeded those required to saturate glucocorticoid receptors in mammalian cells, we postulated a nonspecific physicochemical effect of steroids upon the cell membrane, and therefore tested three noncorticoid steroids for their effects on granulocyte function. All three (conjugated equine estrogen, a synthetic progestogen, and a synthetic androgen) behaved in manner analogous to corticoids at similar concentrations, inhibiting granulocyte aggregation, chemotaxis, and chemiluminescence, as well as binding to the granulocytes of the synthetic oligopeptide agonist f-Met-Leu-Phe. Estrogen was further shown to reduce granulocyte membrane fluidity, assessed by electron paramagnetic resonance. We propose that the unique effects of extremely high-dose corticosteroids are not mediated via the glucocorticoid receptor, but result rather from physicochemical effects of the drugs upon the membranes of effector cells.

Aggregation, chemotaxis, and chemiluminescence of canine granulocytes. Studies utilizing improved cell preparation techniques.

Wishing to extrapolate in vitro observations of granulocyte function and pharmacology made with human cells to animal models of diseases in which we believe granulocyte stimulation to play a major role, we examined techniques for preparation of canine granulocytes and conducted a survey of the function and pharmacology of those cells. Isotonic density gradients of Percoll proved a simple and highly satisfactory method of preparation. Canine granulocytes in most respects paralleled human cells in function and pharmacology, except that canine cells lacked receptors for formylated oligopeptides and resisted them as stimuli; canine plasma contained a heat-labile inhibitor of canine PMN aggregation, oxidative metabolism, and myeloperoxidase release; canine PMNs were not inhibited in aggregation by protease inhibitors such as aprotinin; canine response to ibuprofen and steroids was more variable than that of human cells, and synergy between those agents was less readily demonstrated; heterologous stimulation (canine cells by human C5a or vice versa) led to a different time course and maximum response from those observed in the homologous systems. Canine granulocytes were readily marked with indium-111, and functioned normally in vitro and survived well in vivo after marking. We conclude that the dog is a suitable animal for studying the role of stimulated PMNs in disease, as long as the observed differences are taken into account in experimental design and data interpretation.

Red cell count dependence of whole blood granulocyte luminescence.

To evaluate phagocytosis of granulocyte, chemiluminescence (CL) - measurements were done in whole blood specimen. By this method much less variation (22% versus 84%) could be achieved in the whole blood specimen compared with isolated granulocytes. The quenching of CL by erythrocytes, which is dependent on the quotient erythrocytes/granulocytes, could be significantly reduced by dilution (1:5,000). Optimized reaction conditions were selected (approx. 5 x more sensitive then previous protocols) to evaluate the phagocytic activity of the few remaining granulocytes (approx. 2,000/ml) with routine luminometers.