The additive effect of certain drugs on the cyclosporine A inhibition of human T-cell proliferation. Studies using theophyllamine, warfarin, verapamil and dipyridamol

A pilot study evaluating biomarker development for drug-induced chronic eczematous eruptions of aging individuals

Background

Identifying the drug(s) responsible for drug-induced chronic eczematous eruptions of aging individuals (CEEA) is a clinical challenge in patients on multiple medications. Reliable in vitro testing methods and biomarkers are needed to identify the causative agent and allow simultaneous assessment of T-cell responses to multiple drugs being taken concurrently. This study examined the feasibility of using in vitro, drug-specific T cell activation responses as a biomarker for drug-induced CEEA.

Methods

This was a single center, proof-of-concept pilot study at the University of Utah Hospital, Salt Lake City, Utah. Eight aging study subjects having a history suggestive of chronic eczematous drug eruptions suspected to have resulted from calcium channel blocker (CCB) and/or hydrochlorothiazide (HCTZ) hypersensitivity plus three matched aging control subjects were identified. Drug patch testing for CCB and/or HCTZ, in vitro drug antigen-induced lymphocyte proliferation assays, and multianalyte-determined cytokine release assays were performed before and after HCTZ and/or CCB incubation.

Results

All study and control subject blood samples tested failed to demonstrate detectable enhanced lymphocyte proliferation or cytokine release to in vitro CCBs or HCTZ challenge when tested with a fairly wide range of drug concentrations. Additionally, none of the enrolled patients developed a positive patch test to CCBs and/or HCTZ.

Conclusions

This pilot study aimed to correlate in vitro drug-induced T lymphocyte transformation and cytokine production with the presence of drug-induced CEEA. Failure to identify T cell proliferative responses to CCB drug antigens in our in vitro studies could have, in part, resulted from a pharmacologic inhibiting effect of CCB on T cell activation.

Immunotoxicity of epicutaneously applied anticoagulant rodenticide warfarin: evaluation by contact hypersensitivity to DNCB in rats

The immunotoxicity of epicutaneously administered anticoagulant rodenticide warfarin (WF) was examined in this work by using experimental contact hypersensitivity (CHS) reaction to hapten dinitrochlorobenzene (DNCB). WF (0.05 and 0.5 mg/kg) administration 24 h before the induction of CHS does not change expression of CHS evaluated by ear swelling assay. Regional draining lymph node response during sensitization phase was characterized by decreased cellularity but increased spontaneous and IL-2 stimulated proliferation of draining lymph node cells (DLC). No changes in IL-2 production and in numbers of CD25(+) cells were noted and even decreased proliferative index (ratio of IL-2 stimulated to unstimulated DLC proliferation) was detected. Increase in granulocyte activity (MTT reduction and adhesion to plastic) was noted following application of WF solely with further increase following subsequent application of DNCB, when granulocyte activation (NBT reduction) was noted also. Access of WF into general circulation might be responsible for observed changes, what was supported by ex vivo changes in DLC and granulocyte functions assessed before initiation of sensitization and by in vitro effect of exogenous WF as well. Differential effects of WF on lymphocytes and granulocytes noted in this study highlight the need for simultaneous testing of both cell type activity what might constitute a more integrated approach in immunotoxicity studies.

In vitro analysis of verapamil-induced immunosuppression: potent inhibition of T cell motility and lymphocytic transmigration through allogeneic endothelial cells

BACKGROUND

Cyclosporine A (CsA) and tacrolimus prevent proliferation but not transendothelial migration of alloreactive lymphocytes into donor organs. As a result, serious adverse effects, such as nephrotoxicity and neurotoxicity, have been observed under CsA/tacrolimus therapy. The incorporation of new drugs with infiltration blocking properties might enhance the efficacy of the current immunosuppressive protocol, allowing lower CsA/tacrolimus dosage. Because Ca2+ plays a critical role in cell-cell interaction, the Ca2+-channel blocker verapamil might be a good cany. didate for supporting CsA/tacrolimus-based therapy.

METHODS

A T-cell endothelial cell coculture model or immobilized immunoglobulin G globulin chimeras were employed to investigate how S- and R- verapamil interfere with the lymphocytic infiltration process. The expression and arrangement of membranous adhesion receptors and cytoskeletal F-actin filaments were analyzed by fluorometric method in the presence of. verapamil.

RESULTS

Both verapamil enantiomers strongly inhibited lymphocyte infiltration. CD4+ and CD8+ T-cells were influenced to a similar extent with regard to horizontal locomotion (CD4+=CD8+), but to a different extent with regard to adhesion and penetration (CD4+ > CD8+). Moreover, penetration was blocked to a higher extent than was adhesion. ID50-values were 31 microM (CD4+-adhesion) and 11 microM (CD4+-penetration). Verapamil reduced P-selectin expression on endothelial cells and effectively down-regulated binding of T-cells to immobilized P-selectin immunoglobulin G globulins (ID50=4.4 microM; CD4+). A verapamil-induced reduction of intracellular F-actin in T-lymphocytes was proven to be mainly responsible for diminished cell locomotion.

CONCLUSIONS

The prevention of CD4+ T-cell penetration by verapamil might argue for its use as an adjunct to CsA/tacrolimus-based immunosuppressive therapy.

Augmentative inhibition of lymphocyte proliferation by cyclosporin A combined with the riminophenazine compounds clofazimine and B669

We have investigated the effects of cyclosporin A (CsA, 3-50 ng/ml) in combination with the riminophenazine agents clofazimine and B669 (60-500 ng/ml) on the mitogen- and alloantigen-activated proliferative responses of human mononuclear leukocytes (MNL), as well as on the phospholipase A2 and Na+, K+- adenosine triphosphatase activities of these cells. When used in combination these agents caused inhibition of the proliferative responses of both mitogen- and alloantigen-activated MNL which was at least additive. Combinations of CsA with the riminophenazines also caused augmentative activation of PLA2 and inhibition of Na+, K+-ATPase. The inhibitory effects of these agents, both individually and in combination, on the Na+, K+-ATPase and proliferative responses of MNL were neutralized by the membrane-stabilizing, lysophospholipid complex-forming agent alpha-tocopherol (vitamin E, 20 microgram/ml). These observations suggest that combinations of CsA with riminophenazines cause interactive enhancement of the activity of PLA2 in MNL leading to lysophospholipid-mediated inactivation of Na+, K+-ATPase and consequent inhibition of the proliferative responses of these cells. In the therapeutic setting combinations of these agents may enable reduction in the dose of CsA required to achieve meaningful immunosuppression with a consequent decrease in the risk of chemotherapy-related organ toxicity.

CD4+ TCR alpha beta+ T-cells developing after allogeneic bone marrow transplantation in patients with chronic myelogenous leukaemia. Dipyridamole inhibits functionally heterogeneous T-cell clones

Dipyridamole inhibited the proliferation of functionally heterogeneous CD4+ TCR alpha beta+ T-cell clones prepared from CML-patients 4-6 weeks after allogeneic bone marrow transplantation. The effect was seen when testing concentrations corresponding to the therapeutic serum level. Dipyridamole caused a dose-dependent inhibition of PHA-stimulated proliferation both for clones dependent on exogenous IL2 and clones undergoing autocrine proliferation. The inhibition was seen when using different accessory cells (PBM or BCL), and also when dipyridamole was present during IL2- or IL4-dependent proliferation of activated T-cells. The effect of dipyridamole was also investigated for 76 T-cell clones (76 CD4+ and 7 CD8+ clones) prepared by different cloning procedures from three patients. Although these clones were heterogeneous with regard to cytotoxic function, lymphokine production or lymphokine responsiveness, dipyridamole inhibited IL2-dependent proliferation of all clones. In addition dipyridamole inhibited proliferation of CML cells.