The effect of prothymosin alpha (ProT alpha) on the survival of DBA/2 mice inoculated with syngeneic tumour cells was studied. DBA/2 mice inoculated intraperitoneally (i.p.) with 2 x 10(5) syngeneic leukaemic L1210 cells developed ascites within 8-12 days and died 10-14 days later. Treatment with ProT alpha consistently inhibited the development of ascites in 20% of the treated animals and prolonged the survival of 40%-60% of the animals up to 70 days. The most effective treatment schedule of ProT alpha was 300 ng/mouse given i.p. at 2-day intervals for 3 weeks followed by a rest period of 7 days, prior to tumour cell inoculation. Peritoneal exudate (PE) cells collected from mice treated with the optimal dose of ProT alpha produced, in the absence of exogenous stimulus, six- to eightfold higher levels of tumour necrosis factor alpha (TNF alpha) than PE cells from control mice. Furthermore these cells exhibited cytotoxic activity against several tumour cell lines including the syngeneic L1210, the TNF-insensitive P815 mastocytoma, the human MOLT-4 lymphoblastic leukaemia, as well as the murine TNF-sensitive L929 fibroblast cell line. Kinetic studies revealed that both production of TNF alpha and tumoricidal activity peaked 7 days after the last injection of ProT alpha and were maintained at high levels over a period of 1 month. Injections with 150 ng ProT alpha slightly improved the survival of mice whereas higher (500 ng and 1000 ng) doses of ProT alpha and a wide range of thymosin alpha 1 doses remained without any effect. PE cells collected from these mice produced extremely low levels of TNF alpha and exhibited negligible tumoricidal activity. Our data demonstrate that ProT alpha has a protective effect in vivo against the growth of adoptively transferred tumour cells and suggest that this effect is, at least in part, mediated by ProT alpha-activated PE cells. These cells were demonstrated to produce high levels of TNF alpha in vitro and to exhibit activity against both TNF-sensitive and TNF-resistant cell lines.

PURPOSE To evaluate the response rate and the immunorestorative properties of subcutaneously administered interferon alfa-2b (IFN-A2b) in patients with advanced renal cell carcinoma (RCC) and to correlate the immune status with the clinical responses. PATIENTS AND METHODS Twenty-six patients with advanced RCC were treated with recombinant IFN-A2b. The dose was increased progressively from 5 x 10(6) IU the first week to 10 x 10(6) IU the second week, and thereafter to 15 x 10(6) IU subcutaneously. RESULTS Four patients (15%) achieved partial responses (PRs), and five patients (19%) had stable disease (S), whereas 17 patients (65%) progressed. In all patients, blood was withdrawn before IFN treatment and monthly thereafter. T lymphocytes after isolation from peripheral blood were tested for proliferation in the autologous mixed lymphocyte reaction (autoMLR) and allogeneic mixed lymphocyte reaction (alloMLR), interleukin-2 (IL-2) production, expression of IL-2 receptors during the alloMLR, and the production of interleukin-1 (IL-1) by peripheral-blood monocytes. Twelve patients were assessable, four patients had a PR, one patient had S, and seven patients had progressive disease. Striking increases were demonstrated in all parameters 1 month after treatment with IFN-A2b in the four patients who responded and the patient with S. Namely, the autoMLR responses showed a mean increase of 250%, the IL-2 production 247%, the expression of IL-2-specific receptors 446%, the alloMLR responses 160%, and the production of IL-1 262%. On the contrary, the nonresponders did not show any change in their overall immune status, and in some, deterioration of the already depressed immunologic functions was observed. CONCLUSIONS Administration of IFN-A2b results in a marked potentiation of deficient cellular immune response in vitro in those patients with RCC who respond to the treatment. This may have prognostic significance, and certainly more patients are required to be studied for definite conclusions.

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