Dendritic cells are the most potent antigen presenting cells responsible for the development of immune responses in cancer. However, it is known that the function of dendritic cells in tumor-bearing hosts is severely compromised. Our previous studies demonstrated that the defects in dendritic cell function are due, to a large extent, to the accumulation of high amounts of lipids - predominantly triglycerides - in a substantial proportion of dendritic cells in tumor-bearing mice and patients with cancer. The dendritic cells accumulation of lipids is likely associated with their up-regulation of a scavenger receptor A. This receptor is primarily responsible for uptake of modified lipids. Here, by using different versions of liquid chromatography-mass spectrometry, we identified several molecular species of oxygenated lipids in plasma of tumor-bearing animals that may be responsible for their uptake and accumulation by dendritic cells via scavenger receptor A-dependent pathway - the effect that may be associated with the loss of dendritic cell's immune surveillance function in cancer. (C) 2011 Elsevier Inc. All rights reserved.