Radioimmunodetection of Melanoma: Preliminary Results of a Prospective Study

A prospective study to evaluate the clinical usefulness of radioimmunodetection of melanoma in clinical practice is ongoing at the National Cancer Institute of Milan, Italy. Technical conditions for the application of the method were previously reported. In this trial, 99mTc-labelled F(ab’) 2 fragments of the 225.28S monoclonal antibody were used against a high molecular weight melanoma associated antigen (HMW-MAA).

Retrospective studies on radioimmunodetection of melanoma have already been made by our group and by other Centers in about 300 patients.

This study concerns the evaluation of the regional extension of primary melanoma. 23 patients with 32 suspected lymphatic involvements of melanoma on the trunk and arms underwent immunoscintigraphy. No false positive results were observed; 3 false negatives, one corresponding to a micrometastasis, were noticed. Specificity corresponds to 100% and sensitivity to 78.6%.

Hollow Fiber Immobilized L-asparaginase: In Vivo and in Vitro Immunological Studies

The enzyme L-asparaginase was covalently immobilized on the inner surface of the hollow fibers utilized in a commercially available dialyzer by the periodate method. After sterilization with gamma radiation the bioreactor was able to metabolize in vivo, 90 per cent of circulating asparagine in two hours. The absence in blood of asparaginase-related protein fragments, released from the hollow fiber immobilized enzyme, was monitored using a specific enzyme-linked immunosorbent assay (ELISA).

Immobilization of Arginase on Hollow Fiber Hemodialyzer

The enzyme arginase, purified from bovine liver, was covalently immobilized by the glutaraldehyde method to the inner surface of Cuprophan hollow fibers of a conventional hemodialyzer with a surface 1.3 m3. The yield of the process was 0.3 μg/cm2 of active enzyme at physiological pH. The immobilization method did not adversely affect the physical and mechanical properties of hollow fibers neither their hemocompatibility. After sterilization with ethylene oxide, the bioreactor was able to metabolize five liters of 50 μM arginine solution at pH 7.4, in six hours.

[Prevalence of Chlamydia pneumoniae in respiratory infections in children: an ambulatory diagnostic problem]

It has been recently suggested that Chlamydia Pneumoniae infection is a common finding among children with acute respiratory diseases. Chlamydia cell culture is difficult and time-consuming to perform. Polymerase chain reaction (PCR) is a more rapid but also more expensive technique used to identify Chlamydia in pharyngeal swab, but it can be performed only in few specialized laboratories. We tested a rapid enzyme immuno-assay to detect Chlamydia in 20 children with respiratory infections (mean age 3.29 years; male:female ratio = 12:8) and in 21 healthy children (mean age 4.70 years male:female ratio = 15:6). Prevalence of Chlamydia isolation from pharyngeal swab was very high in both patients and healthy children without a significative difference in the two considered groups (45% vs 42%, p = 0.8). Specific Chlamydia IgG antibodies were undetectable in all patients and healthy children. Nine out of 20 patients affected by acute respiratory disease were Chlamydia-positive and 11 out 20 were Chlamydia-negative: these two groups didn't differ in regard to clinical and laboratory features, whereas duration of symptoms was significantly longer in Chlamydia-positive patients (9.3 vs 5.5 days, p = 0.014). Our study suggests a high prevalence of Chlamydia pharyngeal swab positivity in both healthy and sick children. Diagnosis of Chlamydia infection was not feasible on the basis of the considered clinical and laboratory findings.

Ciliary neurotrophic factor-induced gene expression in human neuroblastoma cell lines

We have analyzed the response of the human neuroblastoma cell lines SK-N-SH (clone SY5Y) and SK-N-BE to the ciliary neurotrophic factor CNTF. In both cell lines CNTF induced the expression of the mRNA for two transcription factors, c-fos and NGF1A. The induction was rapid and transient reaching a maximum between 30 and 60 min after exposure to CNTF and subsequently declining. The level of induction of both c-fos and NGF1A mRNAs was much higher in SK-N-BE neuroblastoma cells compared to the SY5Y. Both cells express comparable levels of the transcript for the CNTF receptor-alpha. This mRNA was down regulated after 5 days of CNTF stimulation in both cell lines. CNTF also induced increased levels of the transcript for the growth cone associated protein GAP43 in SK-N-BE, but not in SY5Y cells. Induction followed a slower kinetic compared to that observed for c-fos and NGF1A. In fact, the GAP43 mRNA levels increased during 2 days of exposure to CNTF. Morphological analysis of CNTF treated cells showed that SK-N-BE undergo significant differentiation in response to CNTF (increased number of cells with neurites and increased neurite length) while SY5Y did not show appreciable morphological differentiation. These data shows that CNTF may elicit different response in neuroblastoma cell lines.

Nerve growth factor (NGF) in cerebrospinal fluid (CSF) from patients with various neurological disorders

It has been recently shown that NGF is not only involved in the survival and development of sympathetic and neural crest-derived sensory neurons, but also in some mechanisms of the immune system. For this reason, we studied the content of NGF in CSF samples from patients with diseases in which neuroimmunological mechanisms seem to be involved (multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer disease, chronic relapsing polyradiculoneuritis, Guillain-Barré syndrome, and tumors of the nervous system), as well as from a number of normal control subjects. We setup an ELISA aimed at the beta subunit of NGF, obtaining good validation tests and a detection limit of 28 pg beta NGF per ml. None of the samples was found to contain detectable levels of NGF and, when a concentration method for sample enrichment was used, only one patient was NGF-positive. This suggests that NGF is probably not involved in the neuroimmunological mechanisms underlying some inflammatory and degenerative diseases of the nervous system.

Structure-function studies of human ciliary neurotrophic factor

Ciliary neurotrophic factor (CNTF) is a polypeptide that promotes the survival and/or differentiation of a number of neural cell types. Here we present a structural and functional analysis of the human CNTF molecule. Variant proteins were synthesized by Escherichia coli transformed with mutant cDNA constructs, and purified by SDS-polyacrylamide gel electrophoresis and reverse phase high pressure liquid chromatography. Most variant CNTF proteins lacked neurotrophic activity, but two N- and C-terminal deletions (delta 2-14 and delta 173-200, respectively) actually displayed a several-fold increase in specific activity. Loss of biological activity was accompanied by changes in the alpha-helical nature of CNTF as measured by circular dichroism. These data strengthen the proposed similarity between CNTF and the family of hematopoietic cytokines.

In vitro evaluation of nanoparticle formulations containing gangliosides

Due to their poor bioavailability after oral administration, the use of gangliosides in medicine is limited to the parenteral route of administration. In the present study, the association with poly(alkylcyanoacrylate) nanospheres and nanocapsules of monosialoganglioside GM1 and other chemically modified gangliosides was investigated with the aim of developing a colloidal drug delivery system suitable for use by the oral route. Our results show that gangliosides can be successfully associated with a biodegradable cyanoacrylic carrier either in the form of nanospheres or as nanocapsules, avoiding any degradation of the ganglioside molecule during the polymerization process. However, the drug-loading was found to be more efficient for nanocapsules. The amount of GM1 incorporated into nanospheres appeared to be dependent on the alkyl chain length of the cyanoacrylic polymer; this amount was however too low for pharmaceutical purposes. In contrast, nanocapsules allowed the attainment of very high drug encapsulation levels, especially with lipophilic derivatives of GM1, where an increase of lipophilicity has been obtained by chemical esterification of the sialic acid residue. Drug release experiments performed in the absence of enzymes indicated that nanocapsules were stable in acid medium, in which no drug release was observed, while their behaviour in basic medium was found to be affected by the composition of the oily phase and the oil/polymer ratio.

Human neutrophil chemokinesis and polarization induced by hyaluronic acid derivatives

Neutrophils and macrophages are known to undergo significant modifications in their morphology and basal metabolism in response to chemical factors, in particular changes in the shape, movement, phagocytic activity and degranulation. These phenomena often involve an increase in chemokinesis and cellular secretory activity, usually expressed in antimicrobial activity. Once activated, the cells can move quickly towards the source of the stimulus, where they produce and release great amounts of enzymes (e.g. proteases, hydrolases, lysozyme) and reactive oxygen metabolites (e.g. O2-., H2O2, OH.). This study has examined the ability of surfaces of selected biomaterials to influence neutrophil morphology and locomotion. The surface of two films derived from hyaluronic acid derivatives were compared with that of glass. The two hyaluronic acid derivatives, despite having a similar chemical structure, were shown to interact with human neutrophils in different ways. A hyaluronic acid ethyl ester stimulated the whole population of neutrophils to take up a non-spherical morphology (polarize) and to move with a velocity similar to that of N-formyl-methionine-leucine-phenylalanine-stimulated cells on a glass surface. In contrast, only 44% of the examined cells on the surface of hyaluronic acid benzyl ester were polarized and their mean speed was only slightly higher with respect to that found with non-stimulated cells on glass. Moreover, while on the benzyl ester and on glass a correlation between neutrophil circularity (i.e. the shape of the cell) and cell speed was found, the ethyl ester did not show any correlation.

Ganglioside composition changes in spongiform encephalopathies: analyses of 263K scrapie-infected hamster brains

Ganglioside composition in brains of terminally ill LVG/LAK golden Syrian hamsters infected with the 263K strain of the scrapie agent was analyzed. Results were compared to those obtained from noninfected animals matched by age, sex, and strain. Gangliosides extracted from scrapie-infected animals showed little change in major components, while an increased number of new alkali-labile species appeared. Additionally, the animal strain employed demonstrated a significant polymorphism in brain ganglioside composition. No significant changes in incubation time, clinical development or pathologic features of scrapie were associated with this polymorphism.

Production and characterization of monoclonal antibodies to human ciliary neurotrophic factor with defined epitope recognition

Ten mouse hybridoma lines producing monoclonal antibodies (Mabs) against recombinant human ciliary neurotrophic factor (rhCNTF) have been obtained. Two monoclonal antibodies belonging to the IgG1 class were selected and characterized. Their specificity was established by ELISA and Western blotting. Epitopes recognized by the two Mabs were investigated with ELISA and Western blotting by using rhCNTF mutants, rhCNTF fragments and synthetic peptides mimicking different portions of the CNTF molecule. The carboxy-terminal part of the CNTF and particularly the sequence between aa 150 and 159 appeared to constitute the immunodominant group. The fact that certain amino acid sequences of CNTF are conserved among species was utilized to examine the crossreactivity patterns of the two Mabs with rat sciatic nerve CNTF by Western blotting and immunohistochemistry. These antibodies will be useful for studying the distribution of CNTF in the nervous system and in developing an enzyme-linked immunosorbent assay for the quantitative determinations of CNTF in various neuropathologies.

Nerve growth factor antibodies recognize neurotrophin-3

The immunological properties of the neurotrophins NGF, BDNF, and NT-3 were compared using polyclonal and monoclonal antibodies against the beta subunit of mouse NGF. Affinity-purified anti-NGF IgG consistently recognized NGF and NT-3 on Western blots, and inhibited the trophic activity of NGF and NT-3 but not BDNF. In contrast, anti-NGF monoclonal antibodies did not block the trophic activity of either NT-3 or BDNF. These results are consistent with the greater structural overlap between NGF and NT-3 than between NGF and BDNF.

Mechanism of action of the monosialoganglioside GM1 as a modulator of CD4 expression. Evidence that GM1-CD4 interaction triggers dissociation of p56lck from CD4, and CD4 internalization and degradation

Analyzing the mechanisms underlying the capability of the monosialoganglioside GM1 to induce CD4 modulation we observed that GM1 has a dual effect on the CD4 molecule. GM1 treatment of the lymphoma cell line MOLT-3 and CD4-transfected HeLa cells for times shorter than 30 min prevented binding of monoclonal antibodies (mAbs) recognizing epitopes located within the first NH2-terminal domains of CD4, but not of the OKT4 mAb, which binds to the region of CD4 proximal to the transmembrane domain. However, no binding of the OKT4 mAb was observed after a few hours of treatment with GM1 in both MOLT-3 cells and HeLa cells transfected with an intact CD4 molecule, but not in HeLa cells transfected with a CD4 molecule lacking the bulk of the cytoplasmic domain, suggesting that modulation of CD4 by GM1 depends on the integrity of the cytoplasmic domain. GM1 treatment blocked binding of several mAbs which recognize epitopes located within the first two NH2-terminal domains of CD4 and did not induce CD4 down-modulation if MOLT-3 cells were preincubated with the OKT4A or the OKT4 mAbs. Immunoprecipitation studies with [35S]methionine-labeled MOLT-3 cells showed that GM1-induced CD4 down-modulation was accompanied by CD4 degradation, and this was preceded by dissociation of p56lck from CD4. GM1-induced CD4 down-modulation, dissociation of p56lck from CD4, and CD4 degradation were unaffected by staurosporine, which, on the contrary, blocked these events in response to phorbol 12-myristate 13-acetate. These observations demonstrate that the first action of GM1 is to mask epitopes located within the first two NH2-terminal domains; then, GM1 triggers protein kinase C-independent signals which cause p56lck dissociation from CD4 and the delivery of the molecule to an intracellular compartment where it is eventually degraded.

Synthesis and purification of biologically active rat brain-derived neurotrophic factor from Escherichia coli

The cDNA for rat brain-derived neurotrophic factor was cloned as the prepro and mature sequences into two independent expression vectors under control of the T7 promoter. When these vectors were transfected into Escherichia coli the prepro and mature forms of brain-derived neurotrophic factor accounted for about 20% and 25% of total E. coli proteins, and displayed molecular sizes of 26 kDa and 15 kDa, respectively. Mature brain-derived neurotrophic factor was extracted from E. coli inclusion bodies, refolded in the presence of CuCl2 and purified. The resulting protein had an ED50 of 3 ng/ml in supporting survival of cultured embryonic dorsal root ganglion neurons.

Synthesis and preliminary characterisation of new esters of the bacterial polysaccharide gellan

Under the appropriate experimental conditions, ethyl, propyl, and methylprednisolon-21-yl esters of gellan can be obtained without significant degradation. At low degrees of esterification (de), depending on the ester moiety, the products are water-soluble, which allows the influence of hydrophilicity and charge density on their ability to assume an ordered conformation in dilute aqueous solution to be studied. With high de, the products were soluble only in organic solvents (e.g., methyl sulphoxide) with good film-forming capacity. The methylprednisolon-21-yl esters have been characterised in a preliminary manner in terms of drug-release kinetics.

Production of novel monoclonal antibodies against rabbit platelet factor four

Ten hybridomas producing monoclonal antibodies (Mabs) against rabbit platelet factor 4 (PF4) were obtained from the fusion of splenocytes from mice immunized with purified rabbit PF4 and NSO mouse myeloma cells. When the reactivities of these monoclonal antibodies were determined by enzyme-linked immunosorbent assay and immunoblotting with human and rabbit PF4, they showed a high degree of specificity. Only one Mab recognized an epitope common to the human and rabbit molecules, the other nine reacted only with the rabbit protein. All the antibodies recognized, in crude platelet lysates, a band that comigrates with the purified PF4 protein. None of these antibodies cross-reacted with major rabbit or human platelet-poor plasma proteins. The significance of the Mabs in immunological and physiological studies is discussed.

Competitive binding assay for quantitative determination of GM1 ganglioside in plasma and cerebrospinal fluid

A competitive binding assay for the quantitative determination of GM1 ganglioside is described. After extraction from biological fluids, GM1 was incubated with a known amount of cholera toxin B-subunit conjugated with horseradish peroxidase, and exposed to GM1 adsorbed onto polystyrene microwells. Since GM1 in solution blocks the binding of toxin B-subunit to GM1 adsorbed onto the solid phase, enzyme activity serves as a reciprocal measure of GM1 concentration in the sample. The assay was used to determine the basal level of GM1 in plasma and cerebrospinal fluid in different populations.

Synthesis of the biologically active beta-subunit of human nerve growth factor in Escherichia coli

The gene (NGFB) encoding the beta subunit of mature human nerve growth factor (hNGFB) was subcloned into the pJLA503 expression vector under the control of bacteriophage promoters PR and PL, and expressed in Escherichia coli. The recombinant protein represented approximately 3% of the total cellular protein. Biologically active hNGFB was solubilized (0.2% total NGFB) and purified by cation-exchange chromatography and it yielded two bands on polyacrylamide-gel electrophoresis under nonreducing conditions, corresponding to the monomeric (14 kDa) and homodimeric (26.5 kDa) forms of the molecule. Both hNGFB forms were immunopositive on Western blots with rabbit anti-NGFB antibodies; however, following additional purification, only the species corresponding to the hNGFB homodimer was biologically active on cultured chicken dorsal root ganglion neurons. These results demonstrate the feasibility of synthesizing the biologically active form of hNGFB in E. coli.

Interleukin-1 beta regulates proenkephalin gene expression in astrocytes cultured from rat cortex

Glial cells execute essential functions in central nervous system (CNS) development and are also believed to play important roles during gliosis in response to trauma or disease. These developmental and pathological states have also been associated with elevated expression of opioid genes. Because levels of the cytokine interleukin-1 beta (IL-1 beta) increase following CNS lesions, we examined the possible influence of IL-1 beta on the expression of opioid genes in astrocytes cultured from rat cortex. Proenkephalin mRNA expression was stimulated by IL-1 beta in a time- and concentration-dependent manner, being maximal with 5 U/ml IL-1 beta at 4 h. Although the beta-adrenergic agonist isoproterenol was also active, interferon, glutamate, and carbachol were not. Unlike isoproterenol, the actions of IL-1 beta were not associated with a cyclic adenosine monophosphate (AMP)-dependent pathway. Interleukin-1 beta also regulated a proenkephalin-chloramphenicol acetyltransferase fusion gene transiently transfected into astrocytes, with a dose-response similar to that active in proenkephalin mRNA. These effects of IL-1 beta were region-specific, not being observed with either cerebellar or hippocampal astrocytes; however, isoproterenol was active in the latter cell populations. Proenkephalin mRNA in cortical astrocytes was stimulated following a temperature stress. These results suggest that enhanced proenkephalin gene expression in astrocytes by IL-1 beta may be important in neuroimmune interactions and in trauma-induced CNS injury or stress.

Effect of parenteral administration of GM1 on cytokines and anti-ganglioside antibody patterns. Preliminary report in normal human individuals

To assess the effects of monosialoganglioside GM1 on some immunological parameters, 12 healthy men were treated with 100 mg GM1 i.m. daily for 15 days. Before and after treatment, the following were studied: (1) serum levels of antibodies against GM1, asialo-GM1 (aGM1), GM2 and GD1b; (2) serum levels of interleukin (IL)-1 beta, IL-2, soluble IL-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma); (3) IL-1 beta and TNF-alpha production by peripheral blood monocytes (PBMO). Anti-ganglioside antibody and cytokine serum levels were not affected by exogenous GM1 administration with the exception of a transient increase in anti-GM1 antibody titer observed in one subject. In addition, no inhibition of IL-1 beta and TNF-alpha production by PBMO was observed. These preliminary data do not support a potential immunogenic or immunomodulatory function for in vivo administered GM1.

Cloning and expression of human ciliary neurotrophic factor

Ciliary neurotrophic factor (CNTF) is a survival factor for avian ciliary ganglion neurons and a variety of other neuronal cell types in vitro. We report here the cloning of the entire genomic sequence encoding human CNTF and its primary structure. Biologically active CNTF has been expressed in Chinese hamster ovary cells from a human genomic DNA clone. Human CNTF has no significant sequence similarity to any previously reported protein, although approximately 84% similarity exists compared with rat and rabbit CNTF. The lack of both an N-terminal signal sequence and consensus sequences for glycosylation or hydrophobic regions, and the fact that active CNTF is expressed but not released into the culture medium of transfected cells, argue in favour of human CNTF as a cytosolic protein. These data provide a basis for understanding the role of CNTF in nervous system physiology and pathology.

A simple method to detect contaminating peptides and amino acids in large-scale ganglioside preparations

A reverse-phase liquid chromatography method was developed to analyse the presence of contaminating peptides and amino acids in large-scale monosialoganglioside preparations. Samples were hydrolysed under controlled conditions and derivatized with phenylisothiocyanate. PTC-amino acids were then separated and identified by HPLC. The sensitivity of the method allowed detection of a least 50 pmoles of amino acid per mg of ganglioside with excellent reproducibility and little or no interference of by-products derived from hydrolysis of the glycosphingolipid. The response was consistently linear for each amino acid within the examined analytical range. The ease and speed of performance make this method a useful tool for rapidly monitoring large-scale extraction and purification processes of biologicals obtained from natural sources.

Differences in induction of c-fos transcription by cholera toxin-derived cyclic AMP and Ca2+ signals in astrocytes and 3T3 fibroblasts

The B subunit of cholera toxin, a protein which binds specifically to membrane ganglioside GM1, is known to affect cell growth and differentiation. To investigate the mechanism of these cellular responses at the nuclear level, we used the induction of c-fos in astrocytes and 3T3 fibroblasts as a model. Northern blot analysis showed that treatment with B subunit provokes a rapid and transient expression of c-fos mRNA, independent of a measurable increase in cyclic AMP. The B subunit signal, which is mediated by Ca2+, was compared to cholera toxin and other agents which increase intracellular cyclic AMP levels. In transient transfection assays of astrocytes and fibroblasts, functional analysis of c-fos promoter deletions was used to identify the elements involved in transcriptional activation by B subunit. In astrocytes, the DNA region including the serum response element and the cyclic AMP response element (CRE) are equally required, whereas 3T3 cells require only the CRE for maximal induction. A synergistic effect of signal transduction was mediated by calcium and cyclic AMP on the CRE, being positive in 3T3 cells and negative in astrocytes. Diverse regulatory elements may be thus involved in responses of different cell types to the same extracellular signal. Furthermore, a single regulatory element (CRE) can integrate both calcium and cyclic AMP signals in the control of gene expression.

Synthesis, purification, and characterization of human ciliary neuronotrophic factor from E. coli

The cDNA for human ciliary neuronotrophic factor (CNTF) has been cloned into an expression vector under the control of the T7 promoter. The BL21 strain of E. coli was transformed with this vector. Human CNTF accounted for about 30% of the total bacterial protein after induction with isopropyl-B-D-thiogalactopyranoside. This human CNTF was purified to homogeneity from inclusion bodies by a combination of ion exchange chromatography and reverse-phase high performance liquid chromatography. The amino-terminal amino acid sequence of the purified protein was identical to the deduced amino acid sequence; however, the methionyl residue has been removed. On SDS-PAGE gels, human CNTF displayed a molecular weight of about 24 kDa, in accord with its deduced molecular mass; a pI of 5.8 indicates the acidic nature of the molecule. A proposed structure for human CNTF includes major alpha helical regions. The ED50 of purified human CNTF was approximately 30 pM, using cultured embryonic day 10 chicken dorsal root ganglion neurons; no activity was observed with neurons from embryonic day 8 ganglia. Polyclonal antibodies prepared against both a synthetic peptide of CNTF and the entire human CNTF protein recognized a single 24 kDa band on Western blots, corresponding to human CNTF. However, only the antibodies against intact CNTF blocked its biological activity. This represents the first molecular expression and purification of human CNTF.

Production and characterization of antibodies to mouse scrapie-amyloid protein elicited by non-carrier linked synthetic peptide immunogens

Two polyclonal antibodies were raised by immunizing rabbits with two non carrier-linked synthetic peptides whose amino acid sequences corresponded to codons 89-107 (peptide P1) and 219-233 (peptide P2) of the translated cDNA sequence of murine PrP protein. These free peptides, whose structural characteristics in solution were studied by circular dichroism, elicited a reasonable immunologic response in animals. Both antibodies still recognized the corresponding immunogens after affinity chromatography purification. However, only antibodies raised to the former sequence reacted by immunoblot with a purified preparation of murine scrapie amyloid protein. These findings are discussed together with their correlation to peptide structure and the effectiveness of this simplified immunization procedure.

Large scale purification and immunological characterization of human placental nerve growth factor

Nerve growth factor (NGF) is a protein which plays a critical role in the development and survival of not only peripheral neurons, but possibly also cholinergic brain neurons. The present study describes a procedure for large scale isolation of human NGF of placental origin, and its immunological characterization. A protein species of approximately 26 kDa was obtained, which cross-reacted with antibodies to mouse NGF. Polyclonal and monoclonal anti-mouse NGF antibodies appeared to recognize different bands within this human NGF preparation. Although these polyclonal antibodies recognized both the dimeric and monomeric forms of mouse NGF, the monoclonal antibody recognized only a band corresponding to the dimeric form of mouse NGF.

Purification and characterization of Fab fragments from anti-mouse NGF polyclonal antibodies

A functional role for Nerve Growth Factor (NGF) in the peripheral nervous system is well-documented, but a similar case for NGF in the central nervous system remains to be established. One approach to answering this question would be the availability of high-affinity monospecific Fab fragments obtained against NGF. In the present studies we describe the preparation and characterization of such Fab fragments from anti-mouse NGF polyclonal antibodies. Following their purification by the use of a NGF Sepharose-coupled affinity column, the Fab fragments were examined for biological competence in several ways. In vitro, the anti-Fab fragments blocked the neuronotrophic activity of NGF, as measured by the survival of chicken embryonic day 8 dorsal root ganglion neurons. In vivo, these Fab fragments, when administered systemically to neonatal rats, produced a decrease of noradrenaline levels in two sympathetically innervated organs, the heart and the spleen. These findings suggest that affinity purified Fab fragments of anti-NGF antibodies can be a useful tool for studying the physiological function of NGF in the nervous system.

Peripheral nerve regeneration through a novel bioresorbable nerve guide

A nerve guide made of a benzyl ester of hyaluronic acid (HYAFF11p75) was used to bridge 8 mm gaps in rat tibial nerves. Histologic observations indicated that this biomaterial provoked only a transient, modest inflammatory response, and the resorption rate was compatible with the nerve regeneration processes. Phagocytosis of the biomaterial began after neoangiogenesis and cell migration had taken place from both stumps into the nerve guide material. For comparison, the regeneration achieved was evaluated in nerve guides made of either HYAFF11p75 or Silastic, and in nerves repaired with the autograft technique. Recovery was assessed in vivo 90 days after implantation by measuring the nerve compound action potential (CAP) and conduction velocity (NCV) of the regenerated tibial nerve. The results demonstrate that the nerve guide tubes made of HYAFF11p75 were able to support and direct axonal growth, thereby suggesting a possible use for such biomaterial in the management of short nerve gaps in human pathology.

Chemical residues of ganglioside molecules involved in interactions with lymphocyte surface targets leading to CD4 masking and inhibition of mitogenic proliferation

Human lymphocyte CD4 becomes undetectable in the presence of exogenous gangliosides (CD4 masking), as originally described by Offner et al. (J. Immunol. 1987. 139: 3295). CD4 masking is apparently due to in situ rearrangement of the glycoprotein; since no direct binding of ganglioside to CD4 could be demonstrated, it was suggested that the effect could be mediated by interactions with other, as yet unidentified, surface structures. To gain insight into the structural requirements of the interaction(s) that leads to CD4 masking, we assayed the effects of a battery of gangliosides and of ganglioside derivatives on (a) CD4 masking; (b) cholera toxin binding (as a well known ganglioside-protein interaction) and (c) inhibition of lymphocyte mitogenic proliferation (as a second ganglioside interaction with a lymphocyte surface target). Our results indicate that the three interactions are distinctly different, since ganglioside chemical groups which are essential for one of the interactions are irrelevant for the others, and lead to the conclusion that gangliosides can interact with lymphocyte surface targets in a number of ways, causing a number of independent biological effects.

Evidence for a physiological role of nerve growth factor in the central nervous system of neonatal rats

Forebrain cholinergic neurons have been shown to respond in vivo to administration of nerve growth factor (NGF) with a prominent and selective increase of choline acetyltransferase (ChAT) activity. This has suggested that NGF can act as a trophic factor for these neurons. To test this hypothesis directly, anti-NGF antibodies (and their Fab fragments) were intracerebroventricularly injected into neonatal rats to neutralize endogenously occurring NGF. The anti-NGF antibody administration produced a decrease of ChAT activity in the hippocampus, septal area, cortex, and striatum of rat pups. This finding was substantiated by a concomitant decrease of immunopositive staining for ChAT in the septal area. These effects indicate that the occurrence of endogenous NGF in the CNS is physiologically relevant for regulating the function of forebrain cholinergic neurons.

CD4 modulation and inhibition of HIV-1 infectivity induced by monosialoganglioside GM1 in vitro

The addition of monosialoganglioside GM1 to serum-free culture medium efficiently and specifically inhibited CD4 antigen expression on normal T lymphocytes from peripheral blood or thymus as well as on cells from H9 and Molt-3 lines; other molecules such as CD3, CD2 and CD8 were not affected. Subsequent addition of fetal calf serum or bovine and human serum albumin blocked GM1 action on CD4 expression, most likely through the formation of ganglioside-albumin complexes. Removal of GM1 from the medium was followed by the prompt reappearance of CD4 on the cell surface. GM1 treatment of H9 and Molt-3 cells greatly reduced HIV-1 infectivity, which was evaluated by reverse transcriptase activity levels in culture supernatants and p24 detection on target cells. GM1 also inhibited syncytial formation in Molt-3 cells even when treatment was initiated 24h after infection. The GM1 effect on HIV-1 infectivity, however, was not long-lasting since removal of the compound was followed by a rapid increase in viral replication, probably due to CD4 re-expression and HIV-1 propagation from a few initially infected cells.

Immunoscintigraphy of adenocarcinomas by means of radiolabeled F(ab')2 fragments of an anti-carcinoembryonic antigen monoclonal antibody: a multicenter study

F(ab')2 fragments of anti-carcinoembryonic antigen (CEA) monoclonal antibody F023C5, determined to be more suitable than intact IgG and Fab fragments for immunoscintigraphy, were labeled with 131I or conjugated to DTPA for instant 111In-labeling, and administered i.v. (2-3 mCi/0.5 mg) to 509 patients in 11 nuclear medicine departments: 284 patients had gastrointestinal adenocarcinomas, 204 had nongastrointestinal adenocarcinomas and 21 were control; serum CEA was elevated in 169 patients, normal in 115, and not determined in 225. The following results were obtained: (a) no adverse reactions; (b) tumor imaging in 324 patients (in particular, in 81.5% CEA-seropositive and in 69.0% CEA-seronegative patients); (c) no significant difference in sensitivity among the results of the 11 departments; (d) no significant difference in overall sensitivity between 131I-and 111In-labeled immunoradiopharmaceuticals; (e) the fraction of documented lesions imaged was 73.3% in CEA-seropositive and 53.7% in CEA-seronegative patients; (f) the detection of liver metastases was hampered, particularly when using the 111In-labeled reagent, by nonspecific radioactivity uptake; (g) the major cause of negative immunoscintigraphy results was a lack of CEA in tumor lesions, as documented by immunohistochemistry; (h) lesion size is also important since the sensitivity was 64% for lesions up to 2 cm in diameter and 84% for larger lesions; (i) many "unexpected" radiolocalizations were recorded. Most were identified as occult tumor lesions. In 35 patients, this finding contributed to the early detection of tumor recurrences.

Improved method for purification of human platelet factor 4 by affinity and ion-exchange chromatography

A simple method for the reproducible purification of human platelet factor 4 (PF4) is described. PF4 is obtained in a highly purified form from platelet concentrate by utilizing a combination of affinity and FPLC ion-exchange chromatography. In every instance, after elution from heparin affinity and cation exchange chromatography, SDS gel electrophoresis reveals a single band attributable to PF4. Moreover, the amino acid composition of PF4 isolated by this method is compatible with that described for a PF4 cDNA clone and with other reported PF4 analysis. The purified protein is used to study in vitro the affinity of PF4 for several glycosaminoglycans (GAGs), by measuring the fluorescence of each PF4-GAG complex bound to fluorescamine. PF4 affinity for GAGs is as follows: heparin greater than heparan sulphate much greater than dermatan sulphate.

Lack of suppression by gangliosides of humoral or cellular immunity in vivo

Gangliosides inhibit the proliferative responses of murine and human lymphocytes in vitro, and it has been suggested that they are immunosuppressive in vivo, although no in vivo studies have been performed. In view of the use of gangliosides to treat patients with a variety of neurological disorders, experiments were undertaken to evaluate the possible immunomodulatory effects of gangliosides in vivo. BALB/c mice were injected 5 days a week with buffer, mixed brain gangliosides, or GM1 ganglioside at dosage levels of 30 mg/kg, 60 mg/kg or 90 mg/kg. After 30 days of treatment, the mice were immunized with keyhole limpet hemocyanin or pneumococcal type III polysaccharide and the ganglioside treatment was continued. No differences between treated and control groups were noted in either the magnitude or duration of the antibody response. No differences between groups were noted in the proliferative responses of splenic mononuclear cells to concanavalin A or allogeneic antigens after 9-10 weeks of treatment, nor in the generation of cytotoxic effector cells after 90 days of treatment. Thus, despite the well-documented immunosuppressive effects of gangliosides in vitro, no evidence for a suppressive effect on humoral or cellular immunity in vivo was obtained in these studies.

Immunoscintigraphy of adenocarcinomas by means of 111In-labelled F(ab')2 fragments of anti-CEA monoclonal antibody F023C5

F(ab')2 fragments of F023C5, an anti-CEA monoclonal antibody, were conjugated to diethylenetriamine pentaacetic acid (DTPA) and converted into a ready to use reagent for instant 111In-labelling. The resulting 111In radiopharmaceutical (2-3 mCi/0.5 mg of F(ab')2 fragments) was administered intravenously and tested for its ability to image (at 48-72 h after administration) 31 primary and 85 metastatic carcinoma lesions in 70 adenocarcinoma patients (26 gastrointestinal, 18 breast and 26 lung tumor patients) whose serum CEA was elevated in 43 cases and normal in the other 27. The results were as follows: no adverse reactions or evidence of toxicity were observed in any of the patients. positive immunoscintigraphy results were obtained in 78% CEA-seropositive and in 64% seronegative patients. the fraction of documented lesions which was imaged was 69% in CEA-seropositive patients and 39% in seronegative patients. several 'unexpected' radiolocalizations were imaged; 30/34 were confirmed as (previously occult) tumour lesions in follow-up studies. In 6 patients, the immunoscintigraphic demonstration of previously occult lesions contributed to the early detection of tumour recurrences. the major limitation of the method is the non-specific radioactivity accumulation in the liver, which prevents the detection of liver metastases. in CEA-seropositive patients the fraction of imaged extra-hepatic tumour lesions is over 80%. the major cause of negative immunoscintigraphy results is lack of CEA in the tumour lesion, as demonstrated by immunohistochemistry of surgically removed tumours.

Alpha-fetoprotein Monoclonal Assay: Preliminary Clinical Findings in a High Risk Population

A two-site solid phase immunoradiometric assay was developed for measurement of human alpha-fetoprotein, utilizing two high-affinity monoclonal antibodies directed against distinct and separate epitopes on the proteic structure. The analytical sensitivity of the assay is 0.5 ng/ml. The clinical sensitivity was evaluated by comparison of patients with cirrhosis and patients with hepatocellular carcinoma with cirrhosis. This assay gave good diagnostic discrimination. In a preliminary clinical trial, the specificity of the assay was 92.3%, the clinical sensitivity 88.2%. and predictive values were 78.9% in the clinically positive stage and 96.0% in the negative stage. The diagnostic efficacy of the assay was 91.3%.

Multicenter study of immunoscintigraphy with radiolabeled monoclonal antibodies in patients with melanoma

A multicenter study was performed to analyze the efficacy of 99mTc- and 111In-labeled F(ab')2 fragments of monoclonal antibody (MoAb) 225.28S (reactive with a high molecular weight melanoma associated antigen) to radioimage malignant lesions in patients with melanoma. A total of 254 melanoma patients, carrying 412 documented melanoma lesions, were studied in 10 nuclear medicine departments. A total of 377 lesions were visualized in 206 patients; in particular (a) 250 of 412 known lesions were visualized in 159 of 191 patients known to carry melanoma lesions; (b) 95 occult lesions were visualized in 61 patients of the same group; and (c) 32 lesions were visualized in 15 of 63 patients without diagnosed lesions. The melanomic nature of 101 of 127 radioimaged occult lesions was confirmed by clinical criteria and/or by additional laboratory investigations. These results indicate that immunoscintigraphy with radiolabeled F(ab')2 fragments of MoAb 225.28S can provide clinically useful information. Analysis of the variables influencing the outcome of immunoscintigraphy with 99mTc- and 111In-labeled F(ab')2 fragments of MoAb 225.28S confirmed the role of size, anatomic site, and level of high molecular weight melanoma associated antigen in melanoma lesions. Such analysis also showed, for the first time, the influence (a) of the isotope used to radiolabel the antibody fragments and (b) of the clinical stage of the patients. The present study has shown good agreement in the results obtained by the 10 nuclear medicine departments, suggesting that immunoscintigraphy with radiolabeled F(ab')2 fragments of MoAb 225.28S is a reliable procedure.

Search for HTLV-I and LAV/HTLV-III antibodies in serum and CSF of multiple sclerosis patients

In order to confirm the findings on the presence of antibodies against human T-lymphotropic retroviruses in subjects affected by multiple sclerosis we studied paired serum and CSF samples from 32 MS patients. Both ELISA and Western blot procedures were employed to detect antibodies against HTLV-I and LAV/HTLV-III antigens. Negative results were obtained in all samples examined, except one which was reactive to HTLV-I in ELISA but not in Western blot.

Imaging with 131I-labeled monoclonal antibodies to a high-molecular-weight melanoma-associated antigen in patients with melanoma: efficacy of whole immunoglobulin and its F(ab')2 fragments

In vitro experiments selected optimal conditions to radiolabel with 131I the whole immunoglobulin and F(ab')2 fragments of the monoclonal antibody (MoAb) 225.28S to a high-molecular-weight melanoma-associated antigen (HMW-MAA). Injection of the radiolabeled whole immunoglobulin and F(ab')2 fragments of the MoAb 225.28S into eight patients with melanoma resulted in the accumulation of radioactivity in 10 of 18 metastases. This localization is specific because of the close relationship between detection of HMW-MAA in lesions by immunohistochemical techniques and outcome of immunoscintigraphy and because of the different distribution in tumors and adjacent tissues of radiolabeled F(ab')2 fragments of MoAb 225.28S compared with 99mTc-pertechnetate and with radiolabeled F(ab')2 fragments of MoAb 4C4 to hepatitis B surface antigen. F(ab')2 fragments are superior to whole immunoglobulins to perform immunoscintigraphy, since they markedly reduce the background in bone marrow, liver, and spleen. The sensitivity of the procedure allows the detection of lesions with a diameter of at least 1.5 cm and is influenced by the level of the HMW-MAA in lesions and by their anatomical site.

HBeAg/anti-HBe determination with a new monoclonal immunoradiometric assay

The performance of two assays for the HBeAg/anti-HBe system associated with hepatitis B virus infection, using monoclonal (EBK-Sorin) and polyclonal (HBe-Abbott) antibodies, has been compared. The results on a random population (1,000 samples) demonstrated for the monoclonal reagent a higher sensitivity, without any loss in specificity, and with the further advantage of the use of lower radioactivity levels. The proportion of positives and negatives obtained with the two kits was found to remain unchanged in the case of HBeAg, while a markedly larger percentage of positives (7% higher) was detected for anti-HBe using the monoclonal antibodies.