Association of immune parameters with clinical outcome in stage III colon cancer: results of Southwest Oncology Group Protocol 9009

Levamisole (LMS), utilized in the adjuvant treatment of patients with stage III colon cancer, is immunomodulatory. To determine whether alterations in immune parameters before, during and after 12 months of 5FU/LMS therapy correlate with disease-free survival, 38 patients enrolled on Southwest Oncology Group (SWOG) protocol 8899 received extensive lymphocyte phenotypic analysis prior to therapy and 3, 6, 12 and 15 months after treatment initiation. The median follow-up of patients is 41 months. Significant increases in the proportion and total number of CD56⁺ natural killer cells were seen, starting at 3 months and continuing until 15 months (P < 0.001). Increases in the total numbers of cells expressing CD25 (interleukin-2 receptor), VLA4 and the combinations of CD4: CD45RA and CD4:CDw29 were not evident during therapy but were seen at 15 months (P < 0.05: CD25, CD4:CDw29, CD4:CD45RA; P < 0.001: VLA4). Low levels of CD8⁺ cells prior to treatment initiation and after 3 months of therapy correlated with early relapse within the first year of 5FU/LMS treatment. Patients who have remained disease-free (n = 22, median follow-up 45 months) demonstrated increases in the total numbers of CD8⁺, CD25⁺, CD56⁺, VLA4⁺, CD4: CDw29 and CD4:CD45RA cells, primarily at 15 months. In contrast, patients who relapsed had decreased numbers of CD8⁺, CD4:CDw29, CD4: CD45RA and VLA4⁺ cells and minimal increases in CD56⁺ and CD25⁺ cells. Statistically significant differences between the late-relapse group and the group remaining disease-free were seen for CD25⁺, CD4: CD45RA and CD4:CDw29 cells at the 15-month assay time (P = 0.0276, P = 0.0349, P = 0.0178 respectively). In conclusion, multiple alterations in lymphocyte phenotype, with increases in the proportion and total number of cells involved in cell-mediated immune responses, were seen during and especially following completion of therapy with 5FU/LMS. Many of these changes are significantly associated with clinical outcome and may be useful for risk stratification of stage III colon cancer patients following completion of adjuvant therapy. Received: 9 July 1999 / Accepted: 11 August 1999     

Aging reduces glycerol-3-phosphate acyltransferase activity in activated rat splenic T-lymphocytes

T-lymphocyte proliferation declines with age. Phosphatidic acid (PA) is the precursor to all glycerophospholipids, which serve as important membrane structural components and signaling molecules. Therefore, we tested the hypothesis that aged T-lymphocyte proliferation may be reduced, in part, suppressing phosphatidic acid (PA) biosynthesis. We showed, for the first time, that anti-CD3 stimulation in rat splenic T-lymphocytes selectively increased mitochondrial glycerol-3-phosphate acyltransferase (GPAT) activity. GPAT activity could be further increased by the addition of recombinant acyl-CoA binding protein (rACBP), but the amplification of GPAT activity was blunted by aging. This is important because PA is the precursor lipid for phospholipid synthesis and GPAT is the rate-limiting enzyme in PA biosynthesis. The mechanism by which stimulation and rACBP increased GPAT activity may involve phosphorylation since incubating Jurkat T-lymphocyte mitochondria with casein kinase 2 in vitro significantly increased GPAT activity. The data presented here suggest a novel mechanism by which aging may reduce activation-dependent mitochondrial GPAT activity. This age-induced alteration would result in reduced PA biosynthesis and could explain, in part, the diminished phospholipid content of the membrane and subsequent loss of proliferative capacity in the aged T-lymphocyte.     

An Extracellullar Nuclease from Bacillus Firmus VKPACU-1: Specificity and Mode of Action

An extracellular nuclease from Bacillus firmus VKPACU-1 was multifunctional enzyme, this nuclease hydrolyzed poly U rapidly and more preferentially than the other homopolyribonucleotides. Hydrolysis of RNA this enzyme released mononucleotides in the order 5′UMP > 5′AMP > 5′GMP where as in hydrolysis of DNA the mononucleotides in the order of 5′dAMP > 5′dGMP > 5′dTMP and oligonucleotides. Uridylic linkages in RNA and adenylic linkages in DNA were preferentially cleaved by the nuclease. Nuclease produced oligonucleotides having only 3’ hydroxyl and 5’ phosphate termini. Present nuclease hydrolyzed RNA and DNA released oligonucleotides as major end products and mononucleotides, suggesting an endo mode of action.     

Reversibility of oxygen induced inactivation of nitrogenase in some enterobacteria

Aerobic and microaerobic diazotrophs possess numerous oxygen restriction strategies to protect nitrogenase from inactivation by oxygen without interfering with energy generation through oxidative phosphorylation. Protection by conformational change in nitrogenase was first detected and described in Azotobacter. This strategy once considerd unique for Azotobacter has been shown in this study to occur in Citrobacterfreundii (Braak) Werkman and Gillen and Klebsiella pneumoniae subspecies rhinoscleromatis (Trevisan) Migula also. However, in these enteric bacteria the entire enzyme is not protected probably due to the absence of any respiratory protection similar to that found in the aerobe, Azotobacter.     

Enhanced decolourization of Direct Red-80 dye by the white rot fungus <Emphasis Type="Italic">Phanerochaete chrysosporium</Emphasis> employing sequential design of experiments

Decolourization of Direct Red 80 (DR-80) by the white rot fungus Phanerochaete chrysosporium MTCC 787 was investigated employing sequential design of experiments. Media components for growing the white rot fungus were first screened using Plackett-Burman design and then optimized using response surface methodology (RSM), which resulted in enhancement in the efficiency of dye removal by the fungus. For determining the effect of media constituents on the dye removal, both percent dye decolourization and specific dye removal due to maximum enzyme activity were chosen as the responses from the experiments, and the media constituents glucose, veratryl alcohol, KH₂PO₄, CaCl₂ and MgSO₄ were screened to be the most effective with P values less than 0.05. Central composite design (CCD) followed by RSM in the optimization study revealed the following optimum combinations of the screened media constituents: glucose, 11.9 g l⁻¹; veratryl alcohol, 12.03 mM; KH₂PO₄, 23.08 g l⁻¹; CaCl₂, 2.4 g l⁻¹; MgSO₄, 10.47 g l⁻¹. At the optimum settings of the media constituents, complete dye decolourization (100% removal efficiency) and a maximum specific dye removal due to lignin peroxidase enzyme of 0.24 mg U⁻¹ by the white rot fungus were observed.     

Signal transduction via the T cell antigen receptor in naïve and effector/memory T cells

T cells play an indispensable role in immune defense against infectious agents, but can also be pathogenic. These T cells develop in the thymus, are exported into the periphery as naïve cells and participate in immune responses. Upon recognition of antigen, they are activated and differentiate into effector and memory T cells. While effector T cells carry out the function of the immune response, memory T cells can last up to the life time of the individual, and are activated by subsequent antigenic exposure. Throughout this life cycle, the T cell uses the same receptor for antigen, the T cell Receptor, a complex multi-subunit receptor. Recognition of antigen presented by peptide/MHC complexes on antigen presenting cells unleashes signaling pathways that control T cell activation at each stage. In this review, we discuss the signals regulated by the T cell receptor in naïve and effector/memory T cells.