Biotechnology therapeutics最新文献

Thymus-derived lymphocytes (T cells) are thought to play an important role in the recognition and destruction of neoplastic cells in the host. This principle has provided a foundation for the establishment of therapy with T-cell-stimulating lymphokines, notably interleukin-2, as an approach to the eradication of certain malignancies. Another lymphokine, B-cell-stimulatory factor-1 (BSF-1), also known as IL-4, has also been shown to be capable of inducing T-cell proliferation and cytolytic activity in vitro. We demonstrate herein that in immunosuppressed mice, in vivo IL-4 administration enhances the ability of treated animals to generate cytotoxic T lymphocytes directed against an allogeneic tumor challenge. Moreover, IL-4 is approximately 25 times more effective, on a weight basis, than is IL-2 in augmenting cytotoxic T-lymphocyte activity. This difference in efficiency between the two lymphokines may be partly due to the in vivo half-life. We have found that IL-4 has a serum half-life of 19 +/- 2 min following intravenous administration, in contrast to the half-life of IL-2, which has been reported to be 3.7 min +/- 0.8. These results are not only of interest for our basic understanding of the physiological role of IL-4 but may have immediate importance in clinical settings where lymphokine therapy is contemplated.

Bactenecin is an antimicrobial peptide isolated from bovine neutrophils. Bactenecin was synthesized by solid-phase peptide synthesis and renatured to a fully disulfide bonded form. The peptide inhibits the growth of Escherichia coli and Staphylococcus aureus at the same concentration reported for the peptide purified from bovine neutrophils. Bactenecin inhibits the growth of other medically important bacteria and yeast, and it kills the fungus Trichophyton rubrum. Acetylation and amidation of the amino- and carboxy-termini of bactenecin do not change its potency, while replacement of its two cysteine residues with serine decreases the potency.

The purpose of this study was to analyze the effects of recombinant human interleukin 4 (IL-4) on the differentiation and proliferation in vitro of human granulocyte/macrophage (GM) and erythroid progenitors. IL-4 was added to either fetal bovine serum (FBS)-supplemented or to FBS-deprived cultures of unfractionated human marrow cells or marrow cells depleted of adherent and/or T cells. Paradoxical effects similar to those reported in the murine system were detected in these experiments. In FBS-supplemented cultures, IL-4, which had no effect on the growth or erythroid bursts (from burst-forming cells; BFU-E) detected in the presence of Epo alone, decreased by 46% the number of erythroid bursts detected in the presence of Epo and phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM). In contrast, in FBS-deprived cultures, IL-4 increased by 30-700% the number of erythroid bursts in cultures containing Epo alone or containing Epo, IL-3, and GM-CSF. The stimulatory effect of IL-4 on erythroid burst growth under FBS-deprived conditions was particularly evident when adherent cells were removed. Under the conditions investigated, IL-4 had little effect on the growth of GM colonies. In FBS-deprived suspension cultures of nonadherent, T-cell-depleted marrow cells, IL-4 maintained both the number of BFU-E and CFU-GM for at least 8 days. In these cultures, IL-4 antagonized the capacity of IL-3 to increase the number of BFU-E but IL-4 and IL-3 acted together to maintain the number of CFU-GM. To determine if IL-4 acted directly or indirectly, its effects on the growth of factor-dependent subclones of the murine progenitor cell line 32D were analyzed. Three subclones were studied: the original IL-3-dependent clone 32D cl.3, the Epo-dependent erythroid clone 32D Epo-1, and the G-CSF-dependent myeloid clone 32D G-1. IL-4 alone failed to induce colony growth from these cell lines. However, IL-4 inhibited by 25% the number of colonies formed by 32D cl.3 in the presence of IL-3 while increasing by 25% and 25-50% the number of colonies formed by 32D Epo-1 and 32D G-1 in the presence of Epo or G-CSF, respectively. These results indicate that human IL-4, as its murine counterpart, is a multilineage growth factor with paradoxical effects which are mediated by the direct action of IL-4 on progenitor cells.

The recombinant lymphokine interleukin-2 (IL-2) has activity in renal cell carcinoma, melanoma, and other cancers. A side effect of IL-2 use is a "capillary leak phenomenon" which is purported to be related to endothelial effects of IL-2 itself or to cells activated by IL-2. We studied IL-2 effects on rat lung lavage parameters to determine whether endothelial damage occurred. The specific endpoints were 125I-albumin extravasation, lavage protein, and lavage angiotensin-converting enzyme (ACE) activity. To ensure sensitivity of these endpoints, we used the known endothelial toxicant thiourea, which increases lung lavage protein and lavage ACE. We found that both PEG IL-2 and thiourea increased the amount of protein and 125-I flux into the lavage. However, although thiourea increased lavage ACE, PEG IL-2 did not. These results suggest that PEG IL-2 can increase protein and iodine flux across the endothelium without causing cell injury.

The clinical potential and the limitations of synthetic muramyl peptides have been suggested through extensive work describing their immunomodulating properties and toxicology. The intent of this paper is to offer the clinician a summary of these studies and to introduce the reader to the biological effects associated with administration of muramyl peptides.

Recombinant methionyl human growth hormone (hGH) was administered intratracheally to adult rats, and serum concentrations of immunoreactive hGH were measured for up to 24 h. The mean absolute bioavailability was approximately 36% after 18h and was similar for doses of 0.75, 1.5, and 3 mg/kg. Peak serum hGH concentrations occurred at approximately 6 h after dosing. Tritiated hGH (3H-hGH) was used to follow the clearance of hormone from the lungs. Disappearance was linear with time and by 24 h approximately 70% of the radioactivity was gone from the lungs (elimination half-life = approximately 10.5h). Monomeric and aggregated hGH appeared to account for the majority of the residual 30% of radioactivity. Immunohistochemical localization of hGH in the alveoli suggested that the hormone was concentrated in a thin layer at the air-epithelial boundary. Pulmonary macrophages, which also stained for hGH, probably degrade hGH and thus account for some loss of material in the lungs. These studies suggest that the lung may be an alternative route for systemic delivery of recombinant proteins which are currently delivered by injection.