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Cytotoxic chemotherapies may expose the immune system to high levels of tumor antigens and expand the CD8(+) T-cell response to include weak or subdominant antigens. Here, we evaluated the in vivo CTL response to tumor antigens using a murine mesothelioma tumor cell line transfected with a neotumor antigen, ovalbumin, that contains a known hierarchy of epitopes for MHC class I molecules. We show that as tumors progress, effector CTLs are generated in vivo that focus on the dominant epitope SIINFEKL, although a weak response was seen to one (KVVRFDKL) subdominant epitope. These CTLs did not prevent tumor growth. Cisplatin treatment slowed tumor growth, slightly improved in vivo SIINFEKL presentation to T cells and reduced SIINFEKL-CTL activity. However, the CTL response to KVVRFDKL was amplified, and a response to another subdominant epitope, NAIVFKGL, was revealed. Similarly, gemcitabine cured most mice, slightly enhanced SIINFEKL presentation, reduced SIINFEKL-CTL activity yet drove a significant CTL response to NAIVFKGL, but not KVVRFDKL. These NAIVFKGL-specific CTLs secreted IFNγ and proliferated in response to in vitro NAIVFKGL stimulation. IL-2 treatment during chemotherapy refocused the response to SIINFEKL and simultaneously degraded the cisplatin-driven subdominant CTL response. These data show that chemotherapy reveals weaker tumor antigens to the immune system, a response that could be rationally targeted. Furthermore, while integrating IL-2 into the chemotherapy regimen interfered with the hierarchy of the response, IL-2 or other strategies that support CTL activity could be considered upon completion of chemotherapy.

Candida bombicola (ATCC 22214) and C. apicola (ATCC 96134), grown on glucose (100 g l−1) and arachidonic acid (5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid; AA), 1.25 g l−1, synthesized sophorolipid up to 0.93 g l−1. Acid hydrolysis of sophorolipid yielded 19-hydroxy-5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid (19-HETE) and 20-hydroxy-5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid (20-HETE) which were identified by TLC and GC-MS; the ratio of synthesis was 73:27, respectively. Conversion of AA by immobilized Candida bombicola, suspended in beads of 2% (w/v) calcium alginate for 96 h, gave an 83% conversion of 1 g AA l−1 to 19- and 20-HETE. There was no significant loss in the efficiency of the immobilized cells after ten uses.

The yeast Dipodascopsis uninucleata UOFS Y128 produces 3-hydroxy-5,8,11,14-eicosatetraenoic acid (3-HETE) and 3-hydroxy-5,8,11,14,17-eicosapentaenoic acid (3-HEPE) from arachidonic acid and eicosapentaenoic acid, respectively. The maximal yield of 3-HETE from arachidonic acid was 1.9%: this was achieved by (i) adding arachidonic acid after 46 h growth of a synchronised culture, this being the point at which sexual reproduction and the formation of asci was highest, (ii) using medium buffered to pH 7 in the absence of sucrose and (iii) a fatty acid concentration of 200 mM.