pentostatin and Diabetes-Mellitus--Type-1

Insulin-dependent diabetes mellitus (IDDM) is caused by autoimmune destruction of pancreatic beta cells with the primary mechanism being cell mediated. The BB rat develops insulitis and IDDM with many features analogous to the disease in man. In previous studies we reported that weekly administration of 2'-deoxycoformycin (dCF) for four months reduces significantly the incidence of IDDM in the BB rat by 70%, and that the animals remain free of diabetes for a minimum of two months after drug withdrawal. Since the diabetes-prone BB rat is lymphopenic, with a reduction of both CD4 and CD8 cells, the continuous failure of dCF treated animals to develop diabetes may have been due to generalized immunosuppression. To test this possibility, the ability of dCF treated diabetes-free BB rats to mount an immune response after challenge with Ovalbumin was examined five months after drug withdrawal. The results showed that the post-immunization levels of total IgG and specific IgG in these animals did not differ from those observed in non-dCF treated controls nor those of control diabetes-resistant non-lymphopenic BB rats. Moreover, FACS analysis indicated no change in the percentages of total numbers of CD4+ or CD8+ cells between the two groups of animals. Histological assessment of the pancreata of the post-dCF treated animals showed varying degrees of mononuclear cell infiltrates in the islets. These data demonstrate that treatment by dCF is not permanent, and may require intermittent or continuous administration to prevent development of diabetes. Further studies are needed to determine the mechanism of action of dCF in this model of IDDM.

Topics: Animals; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Diabetes Mellitus, Type 1; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Humans; Immunoglobulin G; Immunosuppressive Agents; Immunotherapy; Islets of Langerhans; Ovalbumin; Pentostatin; Prediabetic State; Rats; Rats, Inbred BB

We have previously reported that weekly administration of the adenosine deaminase inhibitor, 2'-deoxycoformycin (dCF), reduces the incidence of insulin-dependent diabetes mellitus (IDDM) in the BB Wistar rat, and this effect is likely due to immunosuppression by dCF. In the present study, we examined the effect of altering the dose and scheduling of dCF on prevention of IDDM in the BB rat. When rats were treated from day 25 of age with 2.5, 4, or 10 mg of dCF/kg/week, the percentage of diabetes-free animals at 120 days of age was 40, 60, and 80% respectively, compared with 10% for control animals, demonstrating increased protection against IDDM with increased dCF dose. Histological assessment of the pancreata from animals that became diabetic revealed a marked mononuclear infiltrate and a loss of positive staining for beta cell granules. In contrast, pancreata from animals that remained diabetes-free appeared normal. Protection against IDDM by dCF was time dependent and only occurred if treatments were initiated by day 30 of age. In addition, the protective effect persisted after drug withdrawal. Further studies are required to determine the optimum duration of therapy with dCF to prevent IDDM and to examine the immunological mechanism responsible for this effect.

Topics: Aging; Animals; Diabetes Mellitus, Type 1; Immunosuppressive Agents; Male; Pancreas; Pentostatin; Rats; Rats, Inbred BB

The effect of the adenosine deaminase (ADA) inhibitor 2'-deoxycoformycin (dCF) on the development of insulin-dependent diabetes mellitus (IDDM) was assessed in the BB Wistar rat. Sixty-one male rats were treated from days 30 to 120 with 0, 0.5, 1.0 or 1.5 mg dCF/kg/week. The incidence of IDDM was 78% in the controls and was significantly (P < 0.01) decreased in rats receiving 1.5 mg dCF/kg/week (32%), but not in rats receiving lower doses of the drug. However, for those rats that became diabetic the mean time to the development of IDDM was unchanged in animals receiving dCF compared with control. dCF treatment did not produce significant weight loss in the animals or gross changes in the thymus, spleen or kidneys. Although the protective effect of dCF against IDDM was likely produced by immunosuppression, the different dCF dosages had similar effects on ADA suppression in spleen or thymus and on dATP accumulation in these organs.

Topics: Adenosine Deaminase Inhibitors; Animals; Deoxyadenine Nucleotides; Diabetes Mellitus, Type 1; Disease Models, Animal; Dose-Response Relationship, Drug; Male; Organ Size; Pentostatin; Rats; Rats, Inbred BB; Spleen; Thymus Gland

Infusions of syngeneic T-cells, lethally damaged with ultraviolet A light (UVA) and 8-methoxypsoralen (8-MOP), have been reported to prevent or ameliorate a number of autoimmune diseases in humans and in animal models of autoimmune disease. We previously demonstrated that the combination of UVA/8-MOP, or deoxycoformycin and deoxyadenosine (dCF/dAdo), damaged human lymphoid cells by inducing DNA strand breakage and stimulating poly (ADP-ribosyl)ation. These cells subsequently underwent programmed cell death ("apoptosis"). These findings suggested a common mechanism of lymphocyte damage, and that in vitro treatment of T-cells with cCF/dAdo might substitute for UVA/8-MOP. This hypothesis was tested in a model of autoimmune diabetes in the NOD mouse. Young adult female NOD/Wehi mice were given 350 mg/kg cyclophosphamide (CP) on day 1 to induce rapid-onset diabetes and divided into five treatment groups. Four groups received approximately 50 x 10(6) syngeneic mouse splenocytes that had been treated with various cytotoxic agents. 27/40 (68%) of the CP-only control group and 14/30 (48%) of the group given untreated splenocytes developed diabetes. By contrast, only 2/20 (10%) mice of UVA/8-MOP and 3/23 (14%) of dCF/dAdo-treated splenocyte groups developed diabetes (P < 0.01). Diabetes in high spontaneous-diabetes incidence NOD/Lt female mice was also greatly reduced (4/8 untreated vs 1/7 treated; (< 0.05). We postulate that cytotoxic damage to activated splenic T-cells allows their recognition by host T-cells and results in a protective response against autoreactive cells as a form of T-cell vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Apoptosis; Cell Transplantation; Cells, Cultured; Cyclophosphamide; Deoxyadenosines; Diabetes Mellitus, Type 1; DNA Damage; Female; Mice; Mice, Inbred NOD; Pentostatin; Photopheresis; Spleen