Hemolytic assay for venom phospholipase A2.
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Animals↗
Biomedical subjects
C W Vogel
Publications and source records attributed to C W Vogel.
Induction of immune cytolysis: tumor-cell killing by complement is initiated by covalent complex of monoclonal antibody and stable C3/C5 convertase.
The unique specificity of monoclonal antibodies (Ab) was combined with the cell-killing function of the cytolytic alternative pathway of complement. The functionally C3b-like glycoprotein of cobra venom was linked to a murine monoclonal Ab directed to a human melanoma-associated antigen by a disulfide bond, by using a heterobifunctional crosslinking reagent. The covalent monoclonal Ab-cobra venom factor (CVF) complex exhibited specific cytolytic activity in the presence of normal or C4-deficient serum. It induced killing of melanoma cells but not of LG-2 lymphoblastoid cells or P815 mastocytoma cells. The cytolytic action of the monoclonal Ab-CVF complex was selective in that it was limited to the melanoma cells when these were mixed with one of the two other cell lines. In absence of serum, the complex was noncytotoxic. Monoclonal Ab or CVF alone had no cytolytic activity with or without serum. It is concluded that CVF covalently linked to melanoma cell-bound AB forms the stable C3/C5 convertase with factors B and D of the alternative pathway, which in turn causes formation of the membrane attack complex and thereby cell death.
Animals↗
A new cAMP affinity matrix for the rapid purification of protein kinase regulatory subunits.
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Animals↗
Spectrofluorometric and spectrodensitometric determination of chloroquine in plasma and urine.
Chloroquine in a concentration range from 5 ng to 2 mug per ml of biological fluid can be determined in plasma and urine by the spectrofluorometric methods. The spectrodensitometric method is less sensitive and should be used when other drugs are interfering with the chloroquine determination in solution. After extraction from urine and separation from interfering drugs and metabolites by TL-chromatography chloroquine can be determined by spectrodensitometry in a minimum concentration of 5 mug per ml of urine. Chloroquine should be determined in plasma and urine of patients suffering from malaria with an impaired renal function. Whether the fluorometric determination of chloroquine should be used in field investigations will depend on the problem to be investigated and the regional facilities.
Chloroquine↗
Cobra venom factor immunoconjugates: effects of carbohydrate-directed versus amino group-directed conjugation.
Human IgM monoclonal antibody 16-88, derived from patients immunized with autologous colon carcinoma cells, was derivatized with two different cross-linkers, S-(2-thiopyridyl)-L-cysteine hydrazide (TPCH), which is carbohydrate-directed, and N-succinimidyl-3-(2- pyridyldithio)propionate (SPDP), which is amino group-directed. Two antibody functions, antigen binding and complement activation, were assayed upon derivatization with TPCH and SPDP. TPCH allowed for extensive modification (up to 17 TPCH molecules per antibody) without impairment of antigen binding activity, while this function was significantly compromised upon derivatization with SPDP. Antibody molecules derivatized with 16 SPDP residues showed almost complete loss of their antigen binding function. The complement activating ability of antibody 16-88 was significantly decreased after derivatization with TPCH or SPDP. In the case of SPDP derivatization, this decrease of the complement activating ability is predominantly a consequence of the impaired binding function. Upon conjugation of cobra venom factor (CVF), a nontoxic 137-kDa glycoprotein which is capable of activating the alternative pathway of complement, the antigen binding activity of SPDP-derivatized antibody was further compromised, whereas that of TPCH-derivatized antibody remained unaffected even after attachment of three or four CVF molecules per antibody. In both conjugates CVF retained good functional activity. CVF was slightly more active when attached to SPDP-derivatized antibody, suggesting a better accessibility of amino group-coupled CVF for its interaction with other complement proteins. These results indicate that carbohydrate-directed conjugation compromises the antibody function of complement activation, but allows for the generation of immunoconjugates with unimpaired antigen binding capability.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
[Natural human IgM-antibodies in neuroblastoma therapy: preliminary findings of a phase I/II clinical trial].
BACKGROUND: Sera from healthy individuals contain natural IgM antibodies (anti-NB-Ab) cytotoxic to neuroblastoma (NB) cells. In contrast to healthy children the prevalence of anti-NB-Ab in sera of NB patients is low. Binding of anti-NB-Ab to the NB cell surface leads to activation of complement in vitro. In vivo the injection of the purified IgM fraction from a cytotoxic blood donor results in complete growth arrest of NB xenografts in nude rats. Preliminary results from a phase I/II study to evaluate the pharmacokinetics and side effects of a therapy with anti-NB-Ab are presented here. PATIENTS: Included in this study are patients with NB stage 4 according to INSS with relapse or non-responders to therapy according to the GPOH-NB-therapy protocol. The patients are negative for anti-NB-Ab and are older than one year. METHODS: The therapy is based on a complete exchange of the anti-NB-Ab negative patient serum against serum from an anti-NB-Ab positive ABO-compatible donor by means of plasmapheresis. RESULTS: Up to now, 14 cycles of plasmapheresis have been carried out in 6 NB patients. In 13 of 14 therapy cycles a significant increase in serum toxicity could be observed. Severe side effects have not been seen except a catheter associated thrombosis which was reversible under heparin treatment. After plasmapheresis, pain in the tumor site or regions of metastasis did occur regularly. In some cases temporary elevation of body temperature occurred. One patient had a reduced MIBG uptake after therapy. Tumor necrosis was observed in 2 patients. Three patients showed tumor progress. CONCLUSION: Immunotherapy of NB in children by serum exchange using anti-NB-Ab positive ABO-compatible donor serum is feasible without major side effects and leads to a significant increase of serum toxicity against NB cells.
Child↗
Naturally occurring humoral cytotoxicity against neuroblastoma (NB) cells in healthy persons and NB patients.
A novel cytotoxic mechanism against neuroblastoma (NB) cells based on natural immunoglobulin M serum antibodies is described. The occurrence of these antibodies, which are able to induce complement-mediated cytolysis of NB cells, has been investigated in several age groups of healthy persons and in patients with NB. The cytotoxicity of serum samples has been measured in terms of propidium iodide DNA incorporation using a FACScan. The prevalence of anti-NB 1gM antibodies shows a strong age dependence characterized by a nearly complete lack in the first year of life and a steep rise up to 82% beginning with the second year of life. In the sera of 11 NB-bearing patients no cytotoxicity has been found, despite the fact that 8 of these patients were older than 1 year. These findings lead to the hypothesis that natural 1gM antibodies could play a role as an immunological control mechanism against NB.
Antibodies, Neoplasm↗