Conversion of p,p' -DDT to p,p' -DDD by intestinal flora of the rat.

p,p-DDD [1,1-dichloro- 2,2-bis(p-chlorophenyl)-ethane] occurs in the feces and livers of rats, that are given p, p-DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)-ethane] by stomach tube, but not of rats injected intraperitoneally with p,p-DDT. Coliform bacteria, isolated from feces of control animals, can effect reductive dechlorination of p,p-DDT to p,p-DDD. These findings indicate that the normal flora of the gastrointestinal tract, rather than the liver, as others have suggested, is the major source of the p,p-DDD that is found in animals fed p,p-DDT.

Idiotype vaccines against human T cell leukemia. II. Generation and characterization of a monoclonal idiotype cascade (Ab1, Ab2, and Ab3).

Previously, we had generated anti-Id mAb (Ab2) binding to a hybridoma SN2 (Ab1), which recognizes a glycoprotein, gp37, expressed by human leukemic T cells. To characterize these anti-idiotopes further, they were used to immunize mice and rabbits. Several murine anti-anti-Idiotype mAb (Ab3), mostly of IgM-k isotype, were obtained. mAb3 and sera from rabbits immunized with Ab2 contained antibodies that bind to gp37 Ag and leukemic MOLT-4 and JM cells. Also, mAb3 and immune sera from rabbits competed with Ab1 for binding to MOLT-4 cells. They inhibited the binding of iodinated Ab1 to Ab2 indicating that Ab3 in mice and rabbits shares idiotopes with Ab1 (SN2). Furthermore, both the murine mAb3 and rabbit polyclonal Ab3 immunoprecipitated the same gp37 Ag as SN2 (Ab1). The production of Ag-specific Ab3 (Ab1') in mice and rabbits in absence of any exposure to gp37 indicates that these Ab2 may indeed carry the internal image of the gp37 Ag. Such anti-idiotopes (Ab2 beta) may be useful as Ag substitute for the induction of therapeutic immunity in T cell leukemia patients.

Anti-idiotypic monoclonal antibody to a T-cell chronic lymphatic leukemia. Characterization of the antibody, in vitro effector functions and results of therapy.

A murine anti-idiotypic monoclonal antibody (mAb), F1, (IgG2a) was produced against the variable part of the T-cell receptor for antigen (Ti, alpha/beta) on the tumor cells of a patient with T-cell chronic lymphatic leukemia (CD3+,8+,4-). The molecular weight of the protein reactive with mAb F1, comodulation and coprecipitation with anti-CD3 antibody, and the restricted tumor-cell reactivity strongly support the anti-idiotypic nature of mAb F1. MAb F1 also stained less than or equal to 4% of peripheral blood lymphocytes of healthy donors. MAb F1 did not stimulate the tumor cells to DNA synthesis, but stimulated a fraction of the normal peripheral blood lymphocytes, mAb F1 did not mediate antibody-dependent cellular cytotoxicity or complement lysis to any significant degree in vitro. Three infusion of 1-10 mg anti-idiotypic mAb were given over a period of 4 weeks. The plasma half-life for mAb F1 was 3 h in the first 2 h after infusion and 44 h from 2 h to 120 h after infusion. After each treatment a rapid decrease of circulating tumor cells was seen. During the observation period an 80% reduction of the total circulating tumor cells was noted. After the second infusion, IgM and IgG antimouse antibodies were detected. Side-effects from therapy were fever, chills, nausea, vomiting, diarrhea, tachycardia, increase in systolic blood pressure and shortness of breath. Thus, in T-cell malignancies a major reduction of circulating tumor cells can be accomplished by low doses of anti-idiotypic mAb. Anti-idiotypic mAb might be a therapeutic agent of significant importance.

In vivo induction of gamma interferon and tumor necrosis factor by interleukin-2 infusion following intensive chemotherapy or autologous marrow transplantation.

Interleukin-2 (IL-2) therapy may improve immune reconstitution and reduce the risk of leukemic relapse in the setting of minimal residual disease by augmenting cytotoxic effector mechanisms directed at residual malignant cells. In addition, IL-2 in vitro promotes the release of cytokines including gamma-interferon (gamma-IFN) and tumor necrosis factor (TNF), which also possess antileukemic activity and can enhance granulocyte function. To determine if IL-2 infusion induces release of gamma-IFN and TNF in vivo in sufficient quantity to mediate these effects, we have measured serum levels of these cytokines and secretion by lymphocytes obtained from patients receiving this cytokine in a phase 1 trial. Serum gamma-IFN was undetectable pre-IL-2 and increased to 1.5 to 17 U/mL during IL-2 infusion (P less than .05). Culture of patient lymphocytes for 48 hours produced 1.2 U gamma-IFN/2 x 10(6) cells/mL pre-IL-2 rising to 50 U/2 x 10(6) cells/mL when the lymphocytes were obtained during therapy (P less than .05). Lymphocyte subset analysis showed that both CD3+ and CD16+ cells secreted gamma-IFN in response to IL-2. TNF secretion by lymphocytes also rose during IL-2 infusion from a mean of 5 U/mL to 14.4 U/mL (P less than .01) although no rise was seen in serum levels. The material secreted by IL-2-stimulated lymphocytes is bioactive as addition of supernatants from lymphocytes obtained during IL-2 therapy to cultures of myeloid blasts significantly inhibited clonogenic growth. IL-2-induced secretion of these cytokines mediated this inhibition as it could be partially blocked by either anti-gamma-IFN or anti-TNF antibodies. Preincubation of granulocytes with the same supernatants produced enhanced oxidative metabolism, measured by chemiluminescence in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP). This effect also could be partially abrogated by anti-gamma-IFN and anti-TNF antibodies. Therefore, secondary cytokine secretion may boost granulocyte function and contribute to the antileukemic effects of IL-2 infusion in patients following bone marrow transplantation or chemotherapy.