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R van Lambalgen

Publications and source records attributed to R van Lambalgen.

13 recordsLinked to original sources
PubMed1991

Receptor and antibody interactions of human interleukin-3 characterized by mutational analysis.

Human interleukin-3 (hIL-3) is a regulator of proliferation and differentiation of multipotent hemopoietic progenitor cells. Mutants of hIL-3 have been constructed by oligonucleotide-directed mutagenesis and expressed in Escherichia coli and Bacillus licheniformis. Purified muteins were assayed for induction of DNA synthesis in IL-3-dependent human cells and for binding to the IL-3 receptor. Residues at the NH2 and COOH termini together comprising one-quarter of the molecule could be removed without loss of biological function. Deletions of 6-15 residues within the central part of the molecule caused a large reduction (up to 5 logs) but no complete loss of activity. Substitution of evolutionary conserved residues resulted in a strong decrease of biological activity and demonstrated that the S-S bridge is an essential structural element in hIL-3. Interestingly, four muteins displayed a significantly higher potency of binding to the IL-3 receptor than in stimulating DNA synthesis. These results demonstrate that receptor binding may be (partly) disconnected from activation of DNA synthesis. Analysis of hIL-3 muteins demonstrated that the majority of monoclonal antibodies are directed against a small portion of the IL-3 molecule. The neutralizing potential of individual monoclonal antibodies could be increased by a combination of antibodies directed against nonoverlapping epitopes.

Amino Acid Sequence↗
PubMed1990

Induction of monocyte proliferation and HIV expression by IL-3 does not interfere with anti-viral activity of zidovudine.

Myelosuppression is a major symptom in the acquired immunodeficiency syndrome (AIDS). Moreover zidovudine, an anti-retroviral drug used to treat AIDS patients has myelosuppressive side effects. Therefore treatment with IL-3, a multi-lineage hemopoietic growth factor may be beneficial for zidovudine-treated individuals. In this study we examined the effect of IL-3 on human immunodeficiency virus (HIV) expression. The proliferative response to rIL-3 and the effects on the replication of the monocytotropic HIV variant, HTLV-III Ba-L, in the absence or presence of the anti-retroviral drug zidovudine was studied in purified human peripheral blood monocytes. Zidovudine concentrations sufficient for complete inhibition of HIV replication did not affect rIL-3 induced monocyte proliferation. Although rIL-3, like rGM-CSF, was able to augment HIV expression in monocytes, it did not interfere with the anti-retroviral activity of zidovudine. These data indicate that rIL-3 is a potential candidate for use in myelosupportive therapy in AIDS patients treated with anti-retroviral drugs.

Cell Division↗
PubMed1989

Concepts in immunodermatology.

This review describes the various processes which take place in the immunological network of the skin under physiologic or pathological circumstances. A full understanding of the mechanisms in action is important as it could lead to the development of an entirely new class of therapeutics.

Antigen-Presenting Cells↗
PubMed1988

Successful treatment of EAE in rhesus monkeys with MHC class II specific monoclonal antibodies.

Experimental Allergic Encephalomyelitis (EAE) was induced in rhesus monkeys by subcutaneous immunization with calfbrain homogenate in complete Freunds adjuvant. Monkeys were treated with major histocompatibility complex (MHC) Class II specific monoclonal antibodies (MoAb) as soon as the first clinical EAE signs became apparent. Two different treatments were tested. One consisted of 10 daily injections of a mixture of two MHC Class II specific MoAb, reactive with a monomorphic structure of rhesus monkey Class II molecules. The other consisted of 10 daily injections of Genox3.53, specific for HLA-DQW1. This MoAb crossreacts well with monkeys and also detects a polymorphism in this species and is presumably reactive with the RhLA-DQW1 antigen. Both MoAb treatments could modify the clinical course of EAE favourably. Untreated animals invariably died within 3 d of the onset of clinical EAE signs. Only one of the three monkeys treated with the monomorphic MHC Class II MoAb preparation died within 3 d, and the other two survived significantly longer than untreated animals. Both animals treated with Genox3.53 survived significantly longer than untreated control animals. Although only a few animals were tested, these results clearly show the possible beneficial influence of MHC Class II specific MoAb on a T-cell mediated autoimmune disease.

Animals↗
PubMed1988

Side effects and immunogenicity of murine lymphocyte-specific monoclonal antibodies in subhuman primates.

The immediate side effects of lymphocyte-specific monoclonal antibody treatment of nearly 150 monkeys is documented in this study. Immediate side effects were only seen with antibodies specific for CD3 and CD8. These side effects are most likely related to stimulation of T cells to produce lymphokines (CD3) and/or to the rapid cell clearance (CD3 and CD8). No immediate effects were observed when CD4 or major histocompatibility complex class II-specific antibodies were injected. These antibodies may therefore be considered for the treatment of graft rejection or autoimmune diseases. Of the 43 animals that received a monoclonal antibody (MoAb) at least 2 years and up to 5 years prior to this study, none has shown any late effects of MoAb treatment. Most animals tested had a vigorous immune response to the injected MoAbs, both antiidiotypic as well as anti-isotypic antibodies were formed. This response was reduced by using Fab2 fragments or by additional immunosuppression, but it was still high enough to prevent further effectiveness of the MoAb treatment.

Animals↗
PubMed1987

The PIT method: an automated in vitro technique for drug toxicity testing.

An automated in vitro technique for drug toxicity testing is described. Human tumor cells were cultured for 2 days in 96-well microtiter plates before the addition of serial dilutions of drugs. At day 5 the cultures were terminated by the addition of a solution containing propidium iodide, ink and triton X-100 (PIT). Triton X-100 lysed all cells, which were subsequently stained by the DNA specific fluorescing propidium iodide. The ink effectively quenched all background fluorescence. The plates were read on a computer controlled automated microscope with a photomultiplier. The results showed a linear relationship between cell number and fluorescence intensity. Reproducible dose-response curves were obtained for 6 drugs tested. A computer program calculated ID50 values, making use of adequate growth and no-growth controls.

Antineoplastic Agents↗
PubMed1987

Experimental allergic encephalomyelitis in rhesus monkeys: I. Immunological parameters in EAE resistant and susceptible rhesus monkeys.

Immunological parameters in rhesus monkeys, resistant and susceptible to experimental allergic encephalomyelitis (EAE), were studied. Monkeys immunized with complete Freund's adjuvant (CFA) alone and EAE resistant monkeys immunized with a low dose of bovine brain homogenate emulsified in CFA did not show significant fluctuations in numbers of granulocytes, lymphocytes and lymphocyte subsets (CD4; CD8; GM13, a subset of CD8) and anti-brain homogenate antibody titres remained low. EAE susceptible monkeys immunized with a high dose of myelin developed EAE significantly faster than monkeys immunized with a low dose of brain homogenate. During the induction phase all EAE susceptible monkeys, in contrast to the CFA controls and EAE resistant monkeys, showed an increase in the numbers of granulocytes and the CD4/CD8 ratios and had high antibody titres specific for the immunizing antigens. The most significant disease-related changes were observed after the onset of clinical signs. These included a granulocytosis, a lymphopenia and a decrease in the CD4/CD8 ratio, indicating a selective loss of CD4+ lymphocytes. A major difference between monkeys immunized with myelin and brain homogenate was the significant increase in the percentage of GM13+ lymphocytes after the onset of clinical signs in the latter group. Increases in the CD4/CD8 ratio and antibody titres during the induction phase may be prognostic factors for the subsequent development of EAE.

Animals↗
PubMed1986

Sodium azide is less suitable as a positive control of drug-induced lethality for in vitro clonogenic assays.

Sodium azide (6 mg/ml) was used as a positive control for drug-induced lethality in an in vitro clonogenic assay. Petri dishes containing control and sodium azide treated cultures of WiDr cells were placed together in a large Petri dish and incubated at 37 degrees C in an atmosphere of 10% CO2 in air. No growth was observed. Control cells formed colonies only when the dishes were separated from the sodium azide dishes. Using a microtiter plate the toxic effect was inversely related to the distance of the test cultures from the sodium azide treated cultures. These results suggested the formation of a toxic gas or vapour from sodium azide under cell culture conditions, probably an azide. Chemical analysis was based on characteristic reactions, such as the production of a precipitate with silver ions or formation of a red-coloured complex with ferric salts. On a microtiter plate, a gradient of the expected precipitate or red colour was observed, the highest amounts adjacent to the wells containing sodium azide. These results show that sodium azide acts as a positive control of drug-induced lethality for in vitro clonogenic assays. However, the formation of a highly toxic vapour, most likely hydrazaic acid, makes it a less suitable standard.

Azides↗
PubMed1985

Investigations into the principles underlying the automatic reading of tissue typing plates by double fluorochromasia.

The potential advantages of automated microscopy for reading tissue typing results are accuracy and speed. A technique which depends on fluorescence emission of both Carboxy fluorescein (CF) in live cells and Propidium Iodine (PI) in dead cells has been developed. Factors which influence the data have been investigated and appropriate mathematical corrections proposed. A practical guide is given in an appendix. In comparison with other methods double fluorescence was shown to be more accurate than single fluorescence when compared with results obtained by visual reading.

Automation↗
PubMed1979

Curve -shift analysis of cryopreserved killer T cell function.

The conditions for cryopreservation and reconstitution after thawing of cytotoxic effector cells for cell mediated lympholysis (CML) tests are studied. Percentage recovery of functional activity is analysed not by the commonly used method of comparisons at a single concentration of effector cells but by the movement of the curve of functional activity on the axis of cell concentration in culture. By this method the position of the ascending slope of the dose-response curve, at several different effector to target cell ratios, is compared between fresh and frozen-thawed cells. Cooling rates giving optimal recovery were found to vary between experiments. Using simple techniques, optimal cooling rates were found to range from 0.3 to 1.0 degrees C/min, when using dimethyl sulphoxide (10% v/v). Dead cell debris, but not intact dead cells (which take up eosin), were shown to inhibit the lytic ability of functionally active frozen-thawed effector cells. This could be removed by centrifuging the thawed cells over Ficoll-Hypaque. In the recovered population the proportion of cells which excluded the vital dye, eosin, was greater than the proportion of functioning effector cells. This suggested that the cells which excluded eosin contained both functional and nonfunctional, partially damaged effector cells. Thus dye exclusion methods generally over-estimated the functional activity of thawed effector cells. When cells to be used as targets were preserved prior to treatment with phytohaemagglutinin (PHA) no abnormalities were detected in their behaviour to fresh cells.

Aged↗