Regression of malignant melanoma in a dog by local injections of a partially purified preparation containing human alpha-lymphotoxin

Tumour growth inhibition in mice by glycosylated recombinant human lymphotoxin: analysis of tumour-regional mononuclear cells involved with its action

We compared the antitumour effects of glycosylated LT (gLT), nonglycosylated LT and TNF against a solid tumour in mice. We found that: (a) The systemic administration of gLT showed significant antitumour activity. These effects were, however, quite small in nude mice. Nonglycosylated LT and TNF attained the same degree of effectiveness as gLT, but at a 5-times higher dose. The serum half-life of gLT was 3-fold longer than that of nonglycosylated LT and 22-fold longer than that of TNF. (b) The effect of gLT was significantly blocked by pretreatment with anti-asialo GM1 antibody. Treatment with gLT produced a significant reduction in numbers of tumour-regional mononuclear cells, which in turn, produced increases intensive necrosis. (c) Mononuclear cells in the tumour tissues before gLT-injection were predominantly IL-2 receptor +/CD3- cells and CD3+ cells. Pretreatment with the anti-asialo GM1 antibody produced a drastic reduction of IL-2 receptor +/CD3- cells. These findings suggest that the efficient antitumour effect of gLT is due to a longer serum half-life than that of nonglycosylated LT or TNF in vivo, and its function is largely mediated by IL-2 receptor +/CD3- cells.

Synergistic antitumor effect of glycosylated recombinant human lymphotoxin with human interferon-gamma on lymphotoxin-sensitive human tumor

We examined the antitumor effect of glycosylated recombinant lymphotoxin (LT) in combination with human interferon-gamma (IFN-gamma) on human tumors transplanted into nude mice and compared it with that of tumor necrosis factor (TNF). The results were as follows: (i) The systemic administration of glycosylated LT combined with IFN-gamma produced a significant antitumor activity against HT-1080 fibrosarcoma, G-361 malignant melanoma, KB nasopharyngeal carcinoma, and ZR-75-1 breast carcinoma, all of which are relatively resistant to a single treatment with LT or IFN-gamma. The synergistic effect was also seen in LT-sensitive HeLa S3 tumors. The effect was observed after either i.v. or s.c. injection. (ii) In contrast, no synergistic or additive effect on HeLa S3 tumors was observed in the case of TNF combined with IFN-gamma. (iii) The serum half-life of glycosylated LT in tumor-bearing mice was about 22-fold longer than that of TNF. In conclusion, glycosylated LT, especially in combination with IFN-gamma, appears to be a potent cytokine against tumor growth in vivo compared with TNF. Its long serum half-life can result in a strong antitumor effect in combination with IFN-gamma in vivo.

Studies on tumor necrosis factor (TNF). III. Plasma disappearance curves after intramuscular, subcutaneous, intraperitoneal, and oral administration of human recombinant TNF

Since clinical trials with TNF as a therapeutic agent for cancer are in progress, in this study we have chosen to compare the metabolic characteristics of 125I-labeled and unlabeled RTNF after administration through IM, SC, IP and PO routes. Both RTNF and 125I-RTNF plasma concentration profiles showed an absorption phase and a biexponential decline common to all routes of administration. Moreover the pharmacokinetic analysis indicates that TNF blood levels following SC injection are rather similar to those seen after IM dose. No difference has been found in T max. In contrast, the Kel is apparently increased in the SC route, but the difference is not significant. While a prolonged absorption phase had been obtained after IP injection of RTNF, comparison of t 1/2 beta and Kel between IP and SC or IM route failed to reveal significant differences. Surprisingly some plasma TNF bioactivity has been detected following oral administration.

Cloning and expression of cDNA for human lymphotoxin, a lymphokine with tumour necrosis activity

A chemically-synthesized gene and natural complementary DNA coding for human lymphotoxin were isolated and engineered for expression in Escherichia coli. Purified recombinant lymphotoxin shows cytotoxic activity on murine and human tumour cell lines in vitro and causes necrosis of certain murine sarcomas in vivo.

Immunoregulation by lymphokines: immune interferon and lymphotoxin induction of lymphokine activity in human peripheral blood leukocyte cultures

Supernatants of mitogen-induced human PBL cultures contain several lymphokine activities. Analysis of kinetic studies has suggested a correlation in the appearance in culture supernatants of lymphotoxin (LT) and immune interferon (Im-IF). We investigated this interaction between LT and Im-IF in the serum-free human PBL culture system. Partially purified LT was derived from a normal cell line, RPMI 1788. This LT, which had no contaminating IF activity, induced production of significant levels of IF activity as early as 15 hours after initiation of culture. This induced IF activity was identified as Im-IF by criteria of pH 2, SDS and heat sensitivity, as well as neutralization by AB to Im-IF. LT activity, in excess of the units added to the culture, was also measured in the LT-induced cultures. In another group of experiments, partially purified human Im-IF, produced by expression of a cloned gene in monkey COS-7 cells, was added to human PBL cultures. This Im-IF, at concentrations of 160 and 320 units/ml, caused induction of LT activity. The induced LT activity was neutralized by AB raised to 1788-derived LT. Im-IF treated cultures also contained IF activity in excess of the titers added to the cultures. These results would suggest an interaction between LT and Im-IF at the level of production by lymphoid cells.