Aging affect the anti-tumor potential of dendritic cell vaccination, but it can be overcome by co-stimulation with anti-OX40 or anti-4-1BB

It has been well established that there is a decline in immune function with age resulting in a diminished capacity to respond to infections or tumors. Although many studies have demonstrated the efficacy of autologous dendritic cells (DC) vaccines in stimulating an anti-tumor immune response in the young, almost none of these reports consider the effect that aging has on the immune system or test whether DC-vaccination is effective in old hosts. In this study we compared the efficacy of DC-vaccination in young and old mice. Our results showed that DC-vaccination in young animals induced an anti-tumor response resulting in approximately 60% tumor growth inhibition, while minimal protection was observed in old animals. DC vaccination plus rIL-2 further enhanced the anti-tumor response in young animals (approximately 70-75% inhibition), while ineffective in old animals. In contrast, co-administration of anti-OX-40 or anti-4-1BB mAbs vigorously enhanced the anti-tumor immune response in both young (approximately 85-90% inhibition) and old mice (approximately 70-75% inhibition). Our data indicate that although old mice have a decline in immune function, they have the capacity to develop strong anti-tumor responses as long as they are provided with efficient co-stimulation.     

The dif resolvase locus of the Escherichia coli chromosome can be replaced by a 33-bp sequence, but function depends on location.

The dif locus (deletion-induced filamentation) of Escherichia coli is a resolvase site, located in the terminus region of the chromosome, that reduces chromosome multimers to monomers. In strains in which this site has been deleted, a fraction of the cells is filamentous, has abnormal nucleoid structure, and exhibits elevated levels of the SOS repair system. We have demonstrated that a 33-bp sequence, which is sufficient for RecA-independent recombination and which shows similarity to the cer site of pColE1, suppresses the Dif phenotype when inserted in the terminus region. Flanking sequences were not required, since suppression occurred in strains in which dif as well as 12 kb or 173 kb of DNA had been deleted. However, location was important, and insertions at a site 118 kb away from the normal site did not suppress the Dif phenotype. These sites were otherwise still functional, and they exhibited wild-type levels of RecA-independent recombination with dif-containing plasmids and recombined with other chromosomal dif sites to cause deletions and inversions. It is proposed that the functions expressed by a dif site depend on chromosome location and structure, and analysis of these functions provides a way to examine the structure of the terminus region.     

A new system that analyzes erythropoietin-mediated early signal transduction: Transfection of the c-fos enhancer·promoter-luciferase gene into a murine erythroid cell line

Abstract: Erythropoietin (Epo) exerts its effects by binding specific receptors on the surface of reactive cells. However, the signal transduction system after binding has not been well described. To develop a system to analyze the steps of signal transduction, we transfected the human c-fos-enhancer/promoter linked with the Photinus pyralis luciferase gene (pfosluc2) into a murine erythroleukemia cell line ELM-I-1, in which we previously showed that c-fos mRNA is rapidly induced upon Epo-stimulation. A stable transfectant was obtained. The cells transfected with pfosluc2 were stimulated with Epo and luciferase activity in the cells was measured as light intensity. The light intensity integrated for 2 min (LI_2.0) was 3202 ± 80 unit/1.5 × 10₅ cells before stimulation. This increased up to 5869 ± 321 unit/1.5 × 10₅ cells by incubating the cells with 5 U/ml Epo for 2 h. After Epo stimulation, light intensity began to increase at 30 min, reached a peak (about 1.8 times the basal level) at 120 min, and then gradually dropped. The effect of Epo was dose-dependent; significant action occurred at as low as 0.5 U/ml, with a maximum at 5 U/ml. A similar response was observed when the cells were stimulated with interleukin-3 (IL-3) although the response was apparently lower than that with Epo. It was also found that IL-3 had an additive action with Epo on c-fos activity in this system. Thus, the above method was proven to be simple, rapid and sensitive enough to use to determine the early phase of signal transduction of Epo.     

A Ki-1 (CD30)-positive human cell line (Karpas 299) established from a high-grade non-Hodgkin's lymphoma, showing a 2;5 translocation and rearrangement of the T-cell receptor beta-chain gene

We describe the characterization of a new human cell line, Karpas 299 (K299), established from blast cells in the peripheral blood of a 25- year-old white man. His illness, which began with enlarged occipital and axillary nodes and weight loss, ended after 7 months with generalized lymphadenopathy, pleural effusion, and bone marrow involvement. A lymph node biopsy showed a large cell lymphoma mainly sinusoidal in distribution. The blast cells with pleomorphic nuclei resembled primitive histiocytes. The cells, which expressed the T-cell- associated markers CD4 and CD5, were positive for HLA-DR, epithelial membrane antigen, and CD30 (Ki-1 antigen). The karyotype was aneuploid and included a translocation 2;5. The site of translocation on chromosome 5 (at 5q35.1) is in the region of the locus of the c-fms oncogene (receptor of the monocyte-macrophage colony-stimulating factor MCSF or CSF-1). The cell line Karpas 299 has the same karyotype and pattern of antigen expression as the patient's cells. Northern blot analysis of RNA showed an active rearrangement of the T-cell receptor beta-chain gene. This is to our knowledge the first Ki-1 antigen- positive line to be established from a case of non-Hodgkin's lymphoma.