Thomas P. Haverty

A Randomized Clinical Trial Of Induction Therapy With Okt3 In Kidney Transplantation

A randomized, prospective multicenter trial was conducted to compare the safety and efficacy of OKT3 as an induction therapy with that of conventional immunosuppressive therapy administered to cadaveric renal allograft recipients. Two hundred fifteen patients were treated either with OKT3 plus azathioprine and steroids for 14 days with the delayed addition of cyclosporine on day 11, or with conventional immunosuppression (steroids, azathioprine, and cyclosporine). OKT3 patients had significantly fewer rejection episodes (51% vs. 66%, P=0.032), a longer time to initial rejection (46 days vs. 8 days, P=0.001), and fewer rejection episodes per patient (0.82 vs. 1.14, P=0.014) than conventionally treated patients. Kaplan-Meier estimates of two-year graft and patient survival rates were 84% and 95%, respectively, for the OKT3-treated group, and 75% and 94%, respectively, for the conventionally treated group. Following a subsequent first rejection episode, OKT3 reversed 93% of the rejections in patients receiving OKT3 induction therapy and 94% in patients receiving conventional therapy. Adverse experiences reported during OKT3 induction therapy were similar to those seen when the drug was used for rejection. Following initial exposure, 40.3% of the patients tested were positive for anti-OKT3 antibody, only 6.7% of which were of high titer (1:1000). In the presence of low titer (1:100 or less) antibody, OKT3 was successful in reversing rejection in five of six retreated patients tested. In conclusion, treatment with OKT3 (in combination with azathioprine, steroids, and the delayed addition of cyclosporine) is an effective approach for renal allograft maintenance.

Role of insulin and IGF1 receptors in proliferation of cultured renal proximal tubule cells

We have used a murine proximal tubule cell line (MCT cells) to determine the presence and binding characteristics of insulin and IGF1 receptors and to correlate these parameters with the concentration-response relationships for ligand-induced cellular proliferation. Separate insulin and IGF1 receptors were identified by equilibrium binding assays. Half-maximal displacement of either peptide occurred at 3-10 nM; crossover binding to the alternate receptor occurred with a 10- to 100-fold lower affinity. Peptide effects on cellular proliferation were determined by measuring [3H]thymidine incorporation. Both insulin and IGF1 stimulate thymidine incorporation in a dose-dependent manner with similar increases above the basal level. The estimated half-maximal stimulation (EC50) occurred at 4 nM for IGF1 and 8 nM for insulin. A comparison of the receptor binding affinities with the dose-response relationships for [3H]thymidine incorporation reveals that each growth factor appears to be exerting its effect via binding to its own receptor. Therefore, in this cell line, physiologic concentrations of either insulin or IGF1 can modulate cellular growth. To our knowledge this is the first demonstration of a mitogenic effect which may be modulated by ligand binding to the insulin receptor in proximal tubule epithelia.

T Cell recognition of epithelial self

The presentation of self-antigens to circulating T cells is a critical, precipitating event in the induction of autoimmune injury in parenchymal organs. Epithelia expressing these self-antigens are thought to release such moieties for reprocessing by traditional antigen-presenting cells within the lymphoid system. We now demonstrate, however, that some epithelium possess novel functional mechanisms for presenting their own antigens to a responsive, syngeneic T cell repertoire. The presentation of these self-antigens occurs in the context of MHC class II molecules and depends on CD4 associative-recognition determinants. Our findings strongly suggest that organ epithelium may directly activate cell-mediated events to produce autoimmunity through self-recognition.

Murine OKT4A immunosuppression in cadaver donor renal allograft recipients: A cooperative clinical trials in transplantation pilot study

BACKGROUND A phase I study of anti-CD4 immunosuppression of cadaver donor renal allograft recipients was conducted by the NIH Cooperative Clinical Trials in Transplantation to assess safety, tolerability, immunoactivity, and pharmacokinetics of multiple infusions of murine anti-human CD4 monoclonal antibody OKT4A. METHODS Thirty patients were enrolled (August 1992 to October 1993) and received OKT4A at dosages of 0.5 mg/kg (24 patients), 1.0 mg/kg (3 patients), and 2.0 mg/kg (3 patients), beginning and continuing for 12 consecutive days with a standard regimen of cyclosporine, azathioprine, and prednisone. OKT4A treatment was continued after surgery if serum creatinine 24 hr after transplantation was <85% of pretransplantation baseline creatinine. RESULTS Ninety-three percent of patients treated at 0.5 mg/kg OKT4A and all patients at higher doses had mean peak CD4 saturations in excess of 90%. A human anti-mouse antibody response of >3 times pretreatment levels was observed in 84% of patients. There was no evidence of CD4 T cell depletion. OKT4A was well tolerated without first-dose side effects. For the 19 eligible patients treated with 0.5 mg/kg OKT4A with initial graft function, the 3-month treated rejection rate was 37%. The 2-year graft survival rate for all 30 patients enrolled was 83%, and for the 19 eligible patients, 95%. CONCLUSIONS The high percentage of CD4 saturation, the minimal side effects, the observation of a low 3-month rejection rate, and an excellent 2-year graft survival rate in patients treated with 0.5 mg/kg OKT4A support the continued investigation of an anti-CD4 approach to immunosuppressive therapy.

Tubular antigen-binding proteins repress transcription of type IV collagen in the autoimmune target epithelium of experimental interstitial nephritis.

We have been studying immune interactions with somatic cells using a tubular antigen-binding protein (ThF) secreted by helper T lymphocytes harvested from mice that have an autoimmune form of interstitial nephritis called anti-tubular basement membrane disease. This ThF, although characterized originally because of its ability to induce effector T cells, additionally recognizes the nephritogenic 3M-1 antigen expressed by its target renal tubular epithelium. We believe these proteins, in general, may modulate directly some homeostatic functions in organ-derived cells, and now report that our ThF represses specifically the cellular transcription and secretion of basement membrane type IV collagen in tubular epithelium. These in vitro findings of reduced levels of mRNA encoding type IV collagen correlate well with in situ hybridization studies performed on kidneys expressing early autoimmune lesions, and predict a progressive drop in the expression of type IV collagen in the interstitium. Such a novel and unexpected repression of transcription of type IV collagen might easily impart or facilitate permanent change in the infrastructure of kidney architecture during autoimmune injury and, perhaps, contributes to the process of tubular atrophy attendant to prolonged renal inflammation.

1,25-Dihydroxyvitamin D3 stimulates interleukin-2 production by a T cell lymphoma line (MLA-144) cultured in vitamin D-deficient rat serum

A lymphocyte T celt line (MLA‐144), which constitutively secretes interieulin‐2 (IL‐2), was shown to express receptors for 1,25‐diydroxyvitamin D3 (1,25(OH)2 D3). The proliferation of an IL‐2‐dopondent cell line (HT‐2) in response to supernatant! from MLA‐144 cells was employed as an index of IL‐2 production by MLA‐144 cells. IL‐2 production was two fold higher from MLA‐144 cells cultured in 2% vitamin D‐deficient rat serum compared to 10% fetal calf serum (FCS). The addition of 1,25(OH)2D3 at 10‐15 Mor 10‐11 M augmented IL‐2 production by MLA‐144 cells in vitamin D‐deflcient rat serum, but not in fetal calf serum. At 10‐7 M 1,25(OH)2D3 there was inhibition of IL‐2 production by MLA‐144 cells In either vitamin D‐deflcient serum or FCS. There was no effect of 1,25(OH)2D3, added directly to HT‐2 celis. Monoclonal antibody to the IL‐2 receptor competitively inhibited the proliferation of HT‐2 cells in response to MLA‐144 supernatants, suggesting that it was IL‐2 from the MLA‐144 supernatants which influenced HT‐2 proliferation. Our findings demonstrate biphasic does effects of 1,25(OH)2D3 on rymphokine secretion. The use of vitamin D deficient rat serum allowed us to demonstrate the effects of 1,25(OH)2D3 in the physiologic and subphysiologic range.