Anti-tumour effects of interleukin 1 beta: in vivo induction of immunity to B16 melanoma, a non-immunogenic tumour.

The anti-tumour properties of interleukin 1 beta (IL-1 beta) were examined using an intradermal B16 murine melanoma surgical model. B16 cells were injected intradermally on the right ventral side and surgery was performed on days 10-20 to remove the primary tumours. IL-1 beta or vehicle was administered prior to surgery for 5-7 consecutive days. In mice which received only injections of vehicle, survival ranged between 0 and 30% when measured on day 120 after implantation of B16 cells. Mice died of metastases and growth of B16 cells in the thoracic lymph nodes. When mice without metastases were rechallenged with viable B16 cells, only one out of 22 mice (5%) failed to develop tumours. No significant immunity to B16 cells was detected in this group of mice. In contrast, in mice which received injections of IL-1 beta, survival ranged between 70-100% on day 120 after implantation of B16 cells. When IL-1 beta treated mice were rechallenged with viable B16 cells on day 120, 20 out of 32 (63%) mice failed to develop B16 tumours suggesting that some of these mice had immunity to B16 melanoma cells. Moreover, mice with immunity to B16 cells did develop tumours when injected with another syngeneic tumour, MCA 105. In vitro specific immune responses were also demonstrated in spleen cells and sera from mice treated with IL-1 beta, but not in the spleen cells or sera of mice that received only vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo inhibition of tumor growth of B16 melanoma by recombinant interleukin 1 beta. II. Mechanism of inhibition: the role of polymorphonuclear leukocytes.

Recombinant human interleukin 1 beta (IL 1 beta) inhibits growth of B16 melanoma in syngeneic C57BL/6 mice in a dose-dependent manner when given intratumorally, intradermally, or intramuscularly over a period of 5 to 7 days. Inhibition of tumor growth was rapid and measurable within 3 days after the initial injection and occurred regardless of the route of injection. However, only intratumoral (ITU) injections of IL 1 beta resulted in greater than 90% inhibition in tumor growth. This enhanced inhibition of tumor growth was not dependent on T or NK cells since inhibition of tumor growth occurred in nude and Beige mice. Also, a profound lymphopenia occurred in mice receiving IL 1 beta. Inhibition of tumor growth did correlate with an increase in the number of polymorphonuclear leukocytes (PMN's) in the circulation. However, only ITU injections of IL 1 beta increased the number of PMN's within the tumors. IM injections of IL 1 beta, while increasing the number of PMN's in the circulation, did not increase the influx of PMN's into the tumors. Furthermore, the transfer of PMN's directly into B16 tumors caused a 49% reduction in tumor growth without the presence of IL 1 beta. These results suggest that in vivo, PMN's may effectively control the growth of tumors and that IL 1 beta may increase this effectiveness by increasing the number of PMN's in the circulation and by locally stimulating the production of chemotactic factors for PMN's within the tumor.

In vivo inhibition of tumor growth of B16 melanoma by recombinant interleukin 1 beta. I. Tumor inhibition parallels lymphocyte-activating factor activity of interleukin 1 beta proteins.

Seven daily intratumoral injections of human recombinant interleukin 1 beta (rHu-IL 1 beta) inhibit the growth of B16 melanoma in syngeneic female C57BL/6 mice. Inhibition was dose dependent and ranged from 36% to 93%. Other routes of injection of rHu-IL 1 beta (intramuscular, intraperitoneal, intradermal) inhibited tumor growth but to a lesser degree (27% to 50%). Two different rIL 1 beta s, one a mutein of rHu-IL 1 beta (Glu-4) and the other one murine IL 1 beta (rM-IL 1 beta), were tested in the tumor inhibition model. rM-IL 1 beta inhibited tumor growth at lower concentrations than did rHu-IL 1 beta and also had enhanced IL 1 activity in the thymocyte assay in vitro. The mutein of rHu-IL 1 beta (Glu-4) had significantly reduced in vitro IL1 activity and did not inhibit tumor growth. No cytotoxic or cytostatic effects of rHu-IL 1 beta were observed in in vitro assays. These results suggest that rHu-IL 1 beta has antitumor activity in vivo that is probably not due to its direct effects on B16 cells but rather is mediated by secondary effects of IL 1 beta.

Flow cytometric analysis of the effect of interleukin-1 administration on bone marrow populations in mice.

We have examined the effect of administration of human interleukin-1 (IL-1) beta on bone marrow populations in mice. The bone marrow population was characterized by flow cytometric analysis of cell volume, right angle light scatter, and cell surface markers. The bone marrow population demonstrated significant alterations following the injection of a single dose of IL-1. The earliest response was a loss of granulocytes, which was followed by an expansion of cells in this population. There was also an accumulation of kappa chain positive B cells 24 h following administration. These cells were lost from the marrow over the next 48 h, accompanied by an expansion of precursor cells. The changes in cell populations were not due to contaminating lipopolysaccharide (LPS), although the effects could be mimicked by injection of high doses of LPS. Significant effects could be detected with single dose administration of 10 micrograms to 10 ng of IL-1 per animal. The effects of a single high dose (10 micrograms) were mimicked with multiple injections of low doses (5 x 10 ng), suggesting that the intensity of the response is related to the pharmacokinetics of IL-1. These results indicate a potent effect of IL-1 administration on murine bone marrow granulocyte and B lymphocyte populations. The studies described offer a means for the analysis of the effects of IL-1 in vivo.

Muteins of human interleukin-1 that show enhanced bioactivities.

Using recombinant DNA techniques, we have made a series of amino-terminal muteins of human interleukin-1 (IL-1). Two of the muteins demonstrated 4-7-fold increase in bioactivity as compared to that of the native IL-1. The enhanced biological potency coincides with an increase in both receptor binding affinity and in vivo tumor inhibitory activity. By site specific mutagenesis, we have shown that the arginine at the fourth position of IL-1 is one of the key residues in the function of IL-1. Circular dichroism studies of the amino-terminus analogs showed little structural rearrangement. The change in bioactivity might be due to a change in the stability of the muteins, in the side chain interactions with receptors or in the minor change in folding near the receptor binding site.

High-level expression in Escherichia coli of a soluble and fully active recombinant interleukin-1 beta.

A complementary DNA sequence encoding monocyte interleukin-1 (IL-1), beta form/pI7, was expressed in Escherichia coli. Recombinant plasmid pDP516 was constructed by cloning and rebuilding the mature IL-1 coding sequence into an E. coli expression vector. Bacteria transformed with pDP516 constitutively produced recombinant IL-1 (r-IL-1) at 15-20% of total E. coli protein. The r-IL-1 was found to be in the soluble fraction of sonicated E. coli Bacterial r-IL-1 (DP516) has been purified to homogeneity by anion exchange and sizing column chromatography, with an apparent molecular weight of 17,500. The identity of the purified r-IL-1 was confirmed by amino acid and DNA sequencing analyses. Purified recombinant IL-1 DP516 exhibits biological activity similar to that of native monocyte IL-1 (3 approximately 4 X 10(7) units/mg). An amino-terminal deletion mutant completely abolishes the biological activity, indicating that the integrity of the IL-1 molecule might be important for its function.

Features independent of stain intensity for evaluating Feulgen-stained cells.

Eleven features that are independent of stain intensity are described. Values greater than 1.4 times the average optical density were shown to define the visually darker areas of the image, which were considered to be condensed chromatin. Use of the 11 features permitted the discrimination between (1) lymphocytes and macrophages of rats, (2) macrophages from the spleens of rats and monocytes from peripheral blood and (3) macrophages from the spleens of rats injected with complete Freund's adjuvant and those from the spleens of normal rats.

Lens structural disorders in the leopard frog (Rana pipiens) supplied to the laboratory from wild populations.

Examination of lenses of 48 leopard frogs, Rana pipiens, from three commercial suppliers disclosed a high incidence of histologic aberrations. Only four of 17 lenses that appeared totally clear under the dissecting microscope were found to be free of discernible abnormalities on histologic examination. Deviations were most common in the area of elongation. Because of these findings, the applicability of frog lenses for cellular investigations was questioned.

Cellular changes in cultured lenses.

Observations were made on the frog lens epithelium after culture of the entire lens or of capsular explants. General deviations from normal lens structure as well as specific changes in two media were studied. DNA synthesis and mitosis were induced in the central epithelial cells. Disruption of the orderly, single, epithelial layer that is characteristic of normal lenses was accompanied by the appearance of multilayered plaques of epithelial cells and invasion of vacuolated regions of the lens fibers by epithelial cells. Cells that are fibroblast-like in appearance were observed in regions of the capsule depleted of cells and at the free edges of epithelial sheets in cell culture. Epithelial cells were surrounded by capsule-like material even situated in the lens interior. Nuclie derived from central epithelial cells of lenses cultured in L-15 medium and medium 199 had served as donors in previous nuclear transfer experiments in this laboratory. In our current observation of L-15-cultured lenses, cells were sparsely distributed on the capsule and nuclei were abnormally shaped; in 199-cultured lenses, cells were more densely distributed and nuclei resembled those of normal lenses. Medium 199 without serum could better maintain normal lens structure than L-15 medium without serum. In addition, the percentage of epithelial explants demonstrating cellular outgrowth was greater in medium 199. The differences in cellular behavior were shown not to be the result of different sugars, pH, or the presence of CO2. The nuclear transfer results may reflect the structural changes in the epithelium after lens culture in the two media.

Cellular alterations accompany opacification in the cultured lens.

An examination of frog lenses cultured in specific serum-enriched medium was undertaken in order to determine whether such lenses could serve as in vitro models for studying the role of the lens epithelial cell. Histological analysis after sectioning of the lens revealed multilayered epithelial plaques and epithelial invasion of vacuolated cortical fibres, accompanied by the deposition of capsule-like material. A comparison of the effects of two media, L-15 and 199, indicated a greater incidence of opacification induced by L-15, which may be correlated with changes in lens epithelial cell nuclei.