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Biomedical subjects

T F Lint

Publications and source records attributed to T F Lint.

59 records · Page 4Linked to original sources
PubMed1975

Binding of the complement intermediate C56 to zymosan in acute phase human sera.

C56 is known to appear in the fluid phase when zymosan is incubated at 37 degrees C with certain acute phase 'reactor' sera. In the present study, C56 was detected bound to the zymosan particle prior to its appearance free in solution. In reactor sera C56 was formed and released with kinetics similar to that of the generation and decay of a C56-binding site formed when zymosan was incubated with normal serum. Bound and fluid phase C56 was detected only in reactor sera, and was generated only by agents known preferentially to activate the properdin pathway. Elution of C56 from zymosan in hypertonic salt solutions proved to be a convenient step in the partial purification of large amounts of this haemolytically active bimolecular complex.

Binding Sites↗
PubMed1975

Studies on the inhibition of C56-induced lysis (reactive lysis). VI. Modulation of C56-induced lysis polyanions and polycations.

Multiple polyanions and polycations were tested for their ability to influence formation of EC567 from C56, C7, and sheep erythrocytes. Six of 11 polyanions tested, including polyanethol sulfonate, heparin, and dextran sulfate, inhibited this reaction. By contrast, polycations (five or seven tested), including polybrene, protamine, and polyornithine, potentiated formation of EC567. The inhibition was similar to that previously described for anionic serum factors termed C567-INH, while the potentiation seemed to involve neutralization of serum C567-INH. Thus, this step of the complement attack mechanisms seems amenable to modulation by certain polyelectrolytes, and may thereby be susceptible to pharmacologic manipulation.

Animals↗
PubMed1975

Studies on the inhibition of C56-initiated lysis (reactive lysis). V. The roleof C567-INH in the regulation of complement-dependent haemolysis initiated by cobravenom factor.

Activation of the alternative pathway of complement by a factor from cobra venom (CVF) can lead to lysis of unsensitized erythrocytes (E) of some species. In these studies we observed that alterations in CVF-induced lysis could be produced by manipulation of C567-INH, a naturally occurring inhibitory activity which acts on fluid phase C567 complexes. Venom lysis of sheep and guinea-pig E was markedly inhibited by serum fractions having C567-INH activity. Microgram quantities of poly-L-lysine (PLL), molecular weight 180,000, a polycation which is a functional antagonist to C567-INH in serum, potentiated CVF lysis of sheep and guinea-pig E, and permitted the lysis of human E, which are otherwise not suscepticle to CVF lysis. The potentiation of venom lysis by PLL seemed not to be due to alterations in the target cell membrane; furthermore, it in turn was reversed by substances with C567-INH activity. This suggests that the generation of fluid phase C567 complexes contributes to the CVF-induced lysis of erythrocytes of these species, and that the haemolytic potential of fluid phase C567 generated during alternative pathway activation by this means is regulated by C567-INH.

Ammonium Sulfate↗
PubMed1974

Hormonal control of lysosomal enzyme release from human neutrophils. Effects of autonomic agents on enzyme release, phagocytosis, and cylic nucleotide levels.

The purpose of this investigation was to examine the effects of autonomic neurohormones, cyclic nucleotides, and related agents on the immunologic discharge of lysosomal enzymes from, and phagocytosis by, purified human neutrophils. In order to discern the possible intracellular mechanisms by which certain neurohormones influence neutrophil function, the concentrations of cyclic AMP and cyclic GMP in neutrophils were assessed during cell contact with phagocytizable particles and autonomic agents. The model system employed for study was the interaction of purified human neutrophils with rheumatoid arthritic (RA) serum-treated zymosan particles at 37 degrees C in a neutral, balanced salt solution containing glucose. Neutrophils ingested the particles and discharged beta-glucuronidase but not lactate dehydrogenase activity during 30 min of incubation. Treatment of zymosan particles with RA serum was more effective than treatment with normal serum with regard to the extent of both particle uptake and lysosomal enzyme release. During contact of neutrophils with RA serum-treated zymosan particles epinephrine, isoproterenol, and cyclic AMP inhibited both particle ingestion and beta-glucuronidase discharge. These actions of epinephrine were associated with a concomitant elevation of cyclic AMP levels. In contrast to the actions of catecholamines and cyclic AMP, acetylcholine and cyclic GMP accelerated lysosomal enzyme release without affecting particle uptake. The actions of acetylcholine were associated with a concomitant elevation of cyclic GMP levels. Increases in neutrophil levels of cyclic GMP but not of cyclic AMP were associated also with the discharge of beta-glucuronidase provoked by particles in the absence of added cholinergic agents. The data suggest that the immunologic release of lysosomal enzymes from human neutrophils can be regulated by autonomic neurohormones, perhaps via the selective formation of appropriate nucleotides.

Arthritis, Rheumatoid↗