Katalin Török

Formation of γ-glutamyl-taurine in the rat brain

Abstract After intraventricular administration of 14C- or 3H-labelled taurine, γ-glutamyl-taurine was detected in the protein free extract of rat brain using a combination of ion exchange chromatography, electrophoretic separation and thin-layer chromatography. Under in vitro conditions γ-glutamyl-transpeptidase (EC 2.3.2.2.) prepared from rat brain catalyzes the formation of γ-glutamyl-taurine from taurine and glutathione or γ-glutamyl-p-nitroanilide. The enzymes of the γ-glutamyl cycle are presumed to be responsible for the in vivo metabolism of this dipeptide.

Evaluation of different methods for detecting circulating immune complexes. Studies in patients with lung cancer

In a collaborative study involving 7 laboratories, sera from 53 patients with lung cancer, 37 primary and 16 secondary tumours, and sera of 40 healthy blood donors were tested by 19 different assays or assay modifications used for detecting immune complexes. In 12 out of 19 assays, significantly higher immune complex levels were found in the cancer patients than in the healthy subjects. Assays based on interactions between immune complexes and Fc receptors of different cells (lymphocytes, macrophages of platelets) discriminated between cancer patients and health subjects and a high percentage (47-87%) of positivity was observed in such assays in patients with lung cancer. In contrast, none of the tests based on immune complex-complement interactions discriminated between cancer patients and health subjects. Immunochemical analyses of the PEG precipitates obtained from the sera tested revealed that the concentrations of IgG, IgA and C3 were significantly higher in the precipitates obtained from patients sera than from control sera, but no significant differences were seen in IgM and C1q concentrations. A 100% correct classification of individuals tested was obtained on discriminant analysis of results with 3 assays: EA rosette inhibition, ADCC inhibition and C3 concentration in PEG precipitates. Correlation between results obtained with individual sera by the different assays was very poor: significant correlation coefficients were found in only 13% of all possible paired comparisons. Our results suggest that Fc receptor-dependent assays are more suitable for detection and measurement of circulating immune complexes in lung cancer than tests based on interactions with complement.

Myometrial (Na+ + K+)-activated ATPase and its Ca2+ sensitivity

Ouabain-sensitive (Na+ + K+)-ATPase activity in the rat myometrial microsome fraction could only be determined following detergent treatment. The (Na+ + K+)-ATPase activity manifested by detergent treatment proved very stable even to high concentrations of NaN3, in contrast Mg+-ATPase activity was reduced to about 30 percent of the control. The major part of the Mg2+-ATPase in the myometrial membrane preparation was found to be identical with the NaN3-sensitive ATP diphosphohydrolase capable of ATP and ADP hydrolysis. This monovalent-cation-insensitive ATP hydrolysis could be extensively reduced by DMSO. Furthermore DMSO prevented the inactivation of the (Na+ + K+)-ATPase activity. 10-100 microM Ca2+ inhibited the (Na+ + K+)-ATPase activity obtained in the presence of SDS by 15-50 percent. The Ca2+ sensitivity of the enzyme was considerably decreased if the proteins solubilized by the detergent had been separated from the membrane fragments by ultracentrifugation. The inhibitory effect could be regained by combining the supernatant with the pellet. Ca2+ sensitivity of the (Na+ + K+)-ATPase activity was preserved even after removal of the solubilized proteins provided that DMSO had been applied. It appears that a factor in the plasma membrane solubilized by SDS may be responsible for the loss of Ca2+ sensitivity of the (Na+ + K+)-ATPase activity, the solubilization of which can be prevented by DMSO.

Effects of therapy with dialyzable leukocyte extracts containing transfer factor activity on antibody-dependent cytotoxic activity in humans

Abstract The effects of therapy with dialyzable leukocyte extracts (DLE) containing transfer factor on antibody-dependent cellular cytotoxicity (ADCC) were studied in 10 patients in a xenogeneic test system using chicken erythrocytes as target cells. A marked increase in “K” cell activity was observed in 4 patients with originally low cytotoxic capacity, while originally normal ADCC activity was not significantly influenced by DLE treatment. The changes in cytotoxicity were not accompanied by parallel increase in the total Fc-receptor-bearing cell population. The observed stimulation of ADCC by DLE may be a possible mechanism of its therapeutic effects in diseases where ADCC plays a role.

Clinical Correlates of Circulating Immune Complex Levels in Advanced Lung Cancer

Sera from 53 patients with unresectable lung cancer were tested for the presence of immune complexes by 12 assays. 5 assays (EA rosette inhibition, ADCC inhibition, platelet aggregation, IgG and C3 concentrations in PEG precipitates) could discriminate cancer patients from healthy subjects with over 80% reliability. On the basis of 3 assays (EA-I, ADCC-I and PEG-C3) a function allowing a 100% correct classification could be formulated:--(EA-I)--0.5 (ADCC-I) + 2.4 (PEG-C3) greater than 69.3, i.e., results higher than 69.3 are characteristic for cancer patients and lower than 69.3 for normal subjects. The relationship between the immune complex levels and the average survival time was not altered by sex, age, histology and treatment. None of the immune complex assays or their combination were useful for the estimation of individual life expectation.