scholarly journals Cyclosporin A and cyclosporin SDZ PSC 833 enhance anti-CD5 ricin A- chain immunotoxins in human leukemic T cells

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 482-489
Author(s):  
JP Jaffrezou ◽  
BI Sikic ◽  
G Laurent
Keyword(s):  
Cyclosporin A ◽  
Small Population ◽  
High Dose ◽  
Ricin A Chain ◽  
Psc 833 ◽  
A Chain ◽  
Ricin A ◽  
Sdz Psc 833

Recent studies have shown that cyclosporin A (CsA) may affect ricin A- chain immunotoxin (RTA-IT) therapy. In this study, we evaluated the ability of CsA and its nonimmunosuppressive analog, SDZ PSC 833, to enhance anti-CD5 T101 RTA-ITs in vitro. Both 4 mumol/L CsA and 4 mumol/L SDZ PSC 833 significantly and specifically enhanced the cytotoxic activity of T101 RTA-IT on the human lymphoblastic T-cell line, CEM III (101-fold and 105-fold, respectively). Furthermore, these Cs also enhanced the cytotoxicity of the more potent T101 F(ab')2 RTA- IT (ninefold and eightfold, respectively). The effect of human plasma, originating from four patients enrolled in a phase I high-dose CsA regimen, was examined on T101 RTA-IT cytotoxicity on CEM III cells. In each case, with plasma CsA levels between 3,090 and 4,860 ng/mL (2.5 to 4 mumol/L), a significant increase in T101 RTA-IT-mediated cytotoxicity was observed ranging from 31% to 60%. Neither CsA nor SDZ PSC 833 affected the rate of RTA-IT binding, internalization, intracellular trafficking, or degradation. Analysis of internalized T101 RTA-IT molecules showed that these were essentially intact, which suggests that these enhancers may act only on a small population of RTA-ITs that escapes present investigational techniques. In conclusion, because the concentrations used are clinically achievable, Cs appear to be promising agents for in vivo enhancement of RTA-ITs.

Cyclosporin A and cyclosporin SDZ PSC 833 enhance anti-CD5 ricin A- chain immunotoxins in human leukemic T cells

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 482-489 ◽  
Author(s):  
JP Jaffrezou ◽  
BI Sikic ◽  
G Laurent
Keyword(s):  
Cyclosporin A ◽  
Small Population ◽  
High Dose ◽  
Ricin A Chain ◽  
Psc 833 ◽  
A Chain ◽  
Ricin A ◽  
Sdz Psc 833

Abstract Recent studies have shown that cyclosporin A (CsA) may affect ricin A- chain immunotoxin (RTA-IT) therapy. In this study, we evaluated the ability of CsA and its nonimmunosuppressive analog, SDZ PSC 833, to enhance anti-CD5 T101 RTA-ITs in vitro. Both 4 mumol/L CsA and 4 mumol/L SDZ PSC 833 significantly and specifically enhanced the cytotoxic activity of T101 RTA-IT on the human lymphoblastic T-cell line, CEM III (101-fold and 105-fold, respectively). Furthermore, these Cs also enhanced the cytotoxicity of the more potent T101 F(ab')2 RTA- IT (ninefold and eightfold, respectively). The effect of human plasma, originating from four patients enrolled in a phase I high-dose CsA regimen, was examined on T101 RTA-IT cytotoxicity on CEM III cells. In each case, with plasma CsA levels between 3,090 and 4,860 ng/mL (2.5 to 4 mumol/L), a significant increase in T101 RTA-IT-mediated cytotoxicity was observed ranging from 31% to 60%. Neither CsA nor SDZ PSC 833 affected the rate of RTA-IT binding, internalization, intracellular trafficking, or degradation. Analysis of internalized T101 RTA-IT molecules showed that these were essentially intact, which suggests that these enhancers may act only on a small population of RTA-ITs that escapes present investigational techniques. In conclusion, because the concentrations used are clinically achievable, Cs appear to be promising agents for in vivo enhancement of RTA-ITs.

Immunotoxins up to the present day

1989 ◽  
Vol 9 (2) ◽  
pp. 139-156 ◽  
Author(s):  
Francis A. Drobniewski
Keyword(s):  
Clinical Studies ◽  
Polyclonal Antibodies ◽  
Cell Binding ◽  
Ricin A Chain ◽  
Future Role ◽  
A Chain ◽  
Ricin A

Immunotoxins consist of monoclonal or polyclonal antibodies conjugated to bacterial or plant toxins. The toxins used are typically of the A-B type in which a toxic A chain is coupled to a B chain responsible for cell binding and facilitation of A chain entry into the cytosol. Two broad strategies have been followed: coupling intact toxins, or A chains alone, to antibodies. This review examines current progress in in vitro and in vivo research, including recent clinical studies, concentrating principally on ricin or ricin A chain conjugates. The future role of conjugates using membrane-acting toxins, immunolysins, is also discussed.

scholarly journals Cytotoxicity of a cell-reactive immunotoxin containing ricin A chain is potentiated by an anti-immunotoxin containing ricin B chain.

1984 ◽  
Vol 160 (1) ◽  
pp. 341-346 ◽  
Author(s):  
E S Vitetta ◽  
R J Fulton ◽  
J W Uhr
Keyword(s):  
Cell Surface ◽  
Cell Line ◽  
Ricin A Chain ◽  
Daudi Cell ◽  
A Cell ◽  
A Chain ◽  
Ricin A

In vitro killing of the human Daudi cell line by either univalent [F(ab')] or divalent (IgG) forms of rabbit anti-human Ig (RAHIg) coupled to ricin A chain can be specifically potentiated by a "piggyback" treatment with ricin B chain coupled to goat anti-rabbit Ig (GARIg). When cells are treated with univalent immunotoxin (IT) [F(ab') RAHIg-A] and then cultured, IT can be detected on the cell surface for at least 5 h, since GARIg-B can still enhance killing at this time. These results provide a strategy for in vivo use of A chain- and B chain-containing IT.

Comparative Study on Reversal Efficacy of SDZ PSC 833, Cyclosporin a and Verapamil on Multidrug Resistance in vitro and in vivo

1995 ◽  
Vol 34 (2) ◽  
pp. 235-241 ◽  
Author(s):  
Toru Watanabe ◽  
Harumi Tsuge ◽  
Tomoko Oh-Hara ◽  
Mikihiko Naito ◽  
Takashi Tsuruo
Keyword(s):  
Multidrug Resistance ◽  
Comparative Study ◽  
Cyclosporin A ◽  
Psc 833 ◽  
Sdz Psc 833

Effect of Chemical Deglycosylation on the in vivo Fate of Ricin A-Chain

1986 ◽  
Vol 3 (3) ◽  
pp. 189-196 ◽  
Author(s):  
DAVID C. BLAKEY ◽  
PHILIP E. THORPE
Keyword(s):  
Ricin A Chain ◽  
A Chain ◽  
Chemical Deglycosylation ◽  
Ricin A

scholarly journals Retinoic acid disrupts the Golgi apparatus and increases the cytosolic routing of specific protein toxins.

1994 ◽  
Vol 125 (4) ◽  
pp. 743-753 ◽  
Author(s):  
Y N Wu ◽  
M Gadina ◽  
J H Tao-Cheng ◽  
R J Youle
Keyword(s):  
Retinoic Acid ◽  
Golgi Apparatus ◽  
Retinoic Acid Receptor ◽  
Receptor Activation ◽  
Marker Enzyme ◽  
Ricin A Chain ◽  
Acid Receptor ◽  
A Chain ◽  
Ricin A

All-trans retinoic acid can specifically increase receptor mediated intoxication of ricin A chain immunotoxins more than 10,000 times, whereas fluid phase endocytosis of ricin A chain alone or ricin A chain immunotoxins was not influenced by retinoic acid. The immunotoxin activation by retinoic acid does not require RNA or protein synthesis and is not a consequence of increased receptor binding of the immunotoxin. Vitamin D3 and thyroid hormone T3, that activate retinoic acid receptor (RAR) cognates, forming heterodimers with retinoid X receptor (RXR), do not affect the potency of immunotoxins. Among other retinoids tested, 13-cis retinoic acid, which binds neither RAR nor RXR, also increases the potency of the ricin A chain immunotoxin. Therefore, retinoic acid receptor activation does not appear to be necessary for immunotoxin activity. Retinoic acid potentiation of immunotoxins is prevented by brefeldin A (BFA) indicating that in the presence of retinoic acid, the immunotoxin is efficiently routed through the Golgi apparatus en route to the cytoplasm. Directly examining cells with a monoclonal antibody (Mab) against mannosidase II, a Golgi apparatus marker enzyme, demonstrates that the Golgi apparatus changes upon treatment with retinoic acid from a perinuclear network to a diffuse aggregate. Within 60 min after removal of retinoic acid the cell reassembles the perinuclear Golgi network indistinguishable with that of normal control cells. C6-NBD-ceramide, a vital stain for the Golgi apparatus, shows that retinoic acid prevents the fluorescent staining of the Golgi apparatus and eliminates fluorescence of C6-NBD-ceramide prestained Golgi apparatus. Electron microscopy of retinoic acid-treated cells demonstrates the specific absence of any normal looking Golgi apparatus and a perinuclear vacuolar structure very similar to that seen in monensin-treated cells. This vacuolization disappears after removal of the retinoic acid and a perinuclear Golgi stacking reappears. These results indicate that retinoic acid alters intracellular routing, probably through the Golgi apparatus, potentiating immunotoxin activity indepedently of new gene expression. Retinoic acid appears to be a new reagent to manipulate the Golgi apparatus and intracellular traffic. As retinoic acid and immunotoxins are both in clinical trials for cancer therapy, their combined activity in vivo would be interesting to examine.

In vivo cytotoxic efficacy of immunotoxins prepared from anti-CD5 antibody linked to ricin A-chain

1991 ◽  
Vol 34 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Odile Rostaing-Capaillon ◽  
Pierre Casellas
Keyword(s):  
Ricin A Chain ◽  
A Chain ◽  
Ricin A

scholarly journals Effects of therapy with T101 ricin A-chain immunotoxin in two leukemia patients

Blood ◽  
1986 ◽  
Vol 67 (6) ◽  
pp. 1680-1687 ◽  
Author(s):  
G Laurent ◽  
J Pris ◽  
JP Farcet ◽  
P Carayon ◽  
H Blythman ◽  
...  
Keyword(s):  
Target Cells ◽  
Pharmacokinetic Studies ◽  
Facs Analysis ◽  
Ricin A Chain ◽  
Blast Cells ◽  
Rapid Clearance ◽  
A Chain ◽  
Free Antigen ◽  
Ricin A

Abstract Two leukemia patients, refractory to chemotherapy, were treated with T101-ricin A-chain immunotoxin (T101 IT). Patient 1 (T-ALL) received a single 13.5 mg dose of T101 IT IV (12-hour infusion). Patient 2 (B-CLL) was treated with a daily 25 mg dose of T101 IT IV (two-hour infusion) over three consecutive days. Patient 2 also received 300 mg of chloroquine IM on days two and three as enhancer. In vivo binding of T101 IT was demonstrated by FACS analysis using either an antimouse Ig- FITC or anti-A-chain-FITC antibodies. Following IT therapy, the expression of T65 antigen on target cells dropped to 50% and 20% of pretreatment levels, respectively. In patient 1, circulating blast cells remained unsaturated during therapy while in patient 2, cells were fully saturated for four to six hours following each infusion. Pharmacokinetic studies showed a rapid clearance of T101 IT after IV administration. Antimouse and anti-A-chain antibodies could not be detected. There were no treatment-related adverse effects. In patient 1 a rapid but transient decrease of target cells was observed, possibly related to the administration of the antibody part of T101 IT. In contrast, patient 2 showed a 40% reduction of the lymphocyte count, which remained stable over a period of 2 weeks. Such a clinical benefit following IT therapy in patient 2 could be ascribed to the absence of circulating free antigen and the complete saturation of target cells.

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