Immunosuppression by D-penicillamine in vitro. Inhibition of human T lymphocyte proliferation by copper- or ceruloplasmin-dependent generation of hydrogen peroxide and protection by monocytes.

Abstract

It has been suggested that D-penicillamine is active in rheumatoid arthritis because of its capacity to function as a selective inhibitor of T lymphocyte function. The basis for the immunosuppressive action of this drug as well as mechanisms whereby the effect of D-penicillamine could be modified by elements of rheumatoid synovial tissue were examined. As previously reported, D-penicillamine, in the presence of copper ions markedly inhibited mitogen-induced human T lymphocyte DNA synthesis. Since the vast majority of copper in the body exists as an integral part of the ceruloplasmin molecule, the capacity of this cuproprotein to augment D-penicillamine-mediated inhibition of T cell function was examined. The requirement for copper ions could be entirely replaced by purified ceruloplasmin, which had been depleted of nonspecifically bound copper by passage over Chelex-100 columns. The mechanism by which D-penicillamine in the presence of either copper ions or ceruloplasmin caused inhibition of T lymphocyte responsiveness was examined. Partial protection from this inhibitory effect was accomplished by sodium borohydride. While superoxide dismutase had no protective effect, catalase was found to protect lymphocyte responsiveness totally from the inhibitory action of D-penicillamine and either copper ions or ceruloplasmin. Similarly, horseradish peroxidase and myeloperoxidase also protected responsiveness from these inhibitors while boiled catalase was without effect. These results indicate that inhibition of T lymphocyte responsiveness resulted from the generation of hydrogen peroxide. Since a number of cells likely to be present at chronic inflammatory sites, such as mononuclear phagocytes, contain enzymatic mechanisms to degrade hydrogen peroxide, the modulatory influence of these cells on the inhibition of T cell function caused by D-penicillamine and copper was examined. Monocytes, whose function was not suppressed by D-penicillamine and copper, were found to protect T lymphocyte responsiveness from the inhibitory effects of either the mixture of D-penicillamine and CuSO4 or of hydrogen peroxide. By contrast, endothelial cells, fibroblasts, or cells obtained from enzyme-digested noninflamed synovium could not protect T cells from the inhibitory effects of D-penicillamine and copper. Protection of T cells was afforded by means of a heat labile, azide-sensitive soluble factor present in lysates of human monocytes. These results indicate that the mechanism whereby D-penicillamine in the presence of copper or ceruloplasmin inhibits T lymphocyte responsiveness involves the generation of hydrogen peroxide and that other neighboring cells likely to be found w

In vitro production and scavenging of hydrogen peroxide by D‐penicillamine. Relationship to copper availability

“…We have confirmed this possibili- ty by showing that DP scavenges H202 in a direct assay and by demonstrating that DP protects Con Astimulated PBMC from the inhibitory effects of exogenous H202. The production of H202 by DP and copper sulfate occurs rapidly and our data support the concept that the suppressive effect of this combination on in vitro lymphocyte cultures is mediated by H202 (7,15). H202 synthesis was observed at copper concentrations that occur in RA serum and in the range that can be found in synovial fluid (1 4).…”

“…DP together with copper sulfate or Cp-Cu can inhibit T lymphocyte proliferation in vitro (7). T helper cells appear to be particularly sensitive to inhibition by DP and copper sulfate (17,18), although a recent study suggests that B lymphocytes are more sensitive to H202 than are T celis (19).…”

“…Recently, this inhibitory effect was shown to be partly reversible with sodium borohydride, an antioxidant. Furthermore, inhibition was unaffected by superoxide dismutase, but was completely reversed with catalase, an enzyme that degrades hydrogen peroxide (7). We have shown that either exogenously added H202 or H202 released from polymorphonuclear leukocytes and monocytes stimulated with phorbol myristate acetate can inhibit lymphocyte transformation (8,9).…”

Epstein‐Barr virus clonality in lymphomas occurring in patients with rheumatoid arthritis

“…The subsequent study, however, showed that in 9 additional patients, MTX was not the only drug with possible immunosuppressive effects that was given: other treatments, such as corticosteroids and gold therapy, were also used (3). In the present study, the second patient did not have a history of MTX use but was treated with other drugs with known immunosuppressive effects, such as corticosteroids and penicillamine (14). Therefore it seems that while MTX certainly can induce a state of immunosuppression that is sufliciently severe to allow the development of an EBV-positive lymphoma in patients with rheumatic disease, it is not the only drug with this capability.…”

Activation pathways of synovial T lymphocytes. Expression and function of the UM4D4/CDw60 antigen.

“…These include the presence of serologic abnormalities in RA patients, infiltration of the RA synovium with lymphocytes (1), the role of lymphocytes in animal models of RA (2)(3)(4)(5)(6)(7), and modulation of lymphocyte populations or function Jay Higgs' present by drugs or other measures that are used in the treatment of RA (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), such as cyclosporine A (20).…”