Vehicle control or SPM were added to culture every day. evidence for SPM activity in the humoral response. These new findings highlight the potential applications of SPM as endogenous and non-toxic adjuvants, and as anti-inflammatory therapeutic molecules. Introduction Omega-3 and omega-6 polyunsaturated fatty acids (PUFA) have been long praised for their beneficial roles in inflammatory disease and autoimmune disorders (1). However, little is known about the mechanisms responsible for their beneficial effects. In recent years, the identification of CD1B novel PUFA-derived specialized proresolving mediators (SPM) has generated great interest in the regulation of inflammation, particularly in the resolution phase. The resolution of the inflammatory response is critical to maintain homeostasis and prevent disease. Once thought of as a passive process, the resolution phase of inflammation is a multifaceted and dynamic process (2). Newly-identified, endogenous lipid mediators are now recognized as important players in dampening inflammation. These SPM are synthesized through lipoxygenases (LOX) or acetylated cyclooxygenase-2 (Cox-2) mediated pathways (3). SPM constitute separate families, including lipoxins, resolvins, protectins and maresins (4, 5). SPM play important roles during inflammation including the inhibition of neutrophil infiltration, reduction of T cell cytokine production and increased recruitment of monocytes with enhanced phagocytic activity (6C8). In addition, exogenous treatment LJI308 with pro-resolving lipid mediators has been shown to alleviate symptoms in animal models of inflammatory diseases such as colitis, periodontitis, asthma as well as in autoimmune disorders like arthritis (9). Interestingly, SPM and key intermediates have been identified in serum and in important immunological sites including tonsils and the bone marrow, where high numbers of B cells are present (10C13). Nevertheless, little is known about SPM role on lymphocyte function, particularly B cells, and their effect on the adaptive immune response. In this study we asked if SPM, particularly those found present in the spleen, influence B cell function. Our initial analysis focused on several key SPM, none of which as far as we know have been evaluated for activity on human B cells. Since B cells can respond to other lipid mediators such as prostaglandins, we asked whether certain SPM could beneficially stimulate antibody production and B cell function. Materials and Methods Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolo-lipidomics FVB/NJ mouse spleens were suspended in 1. 0 mL cold methanol and gently ground followed by protein precipitation for 12 hr. Samples were next extracted by SPE column and methyl formate fractions were taken for LC-MS/MS-based lipidomics. LC-MS/MS was performed with an Agilent 1100 HPLC (Agilent Technologies, Santa Clara, CA) equipped with an Agilent Eclipse Plus C-18 column (4.6 mm50 mm1.8 m) paired with an ABI Sciex LJI308 Instruments 5500 QRAP linear ion trap triple quadrupole mass spectrometer (Applied Biosystems, Foster LJI308 City, CA). Instrument control and data acquisition were performed using AnalystTM 1.5 software (Applied Biosystems). The mobile phase consisted of methanol/water/acetic acid (55/45/0.01; v/v/v) LJI308 and was ramped to 88/12/0.01 (v/v/v) after 10 min, 100/0/0.01 (v/v/v) after 18 min, and 55:45:0.01 (v/v/v) after 1 minute to wash and equilibrate the column. Mass spectrometry analyses were carried out in negative ion mode using multiple reaction monitoring (MRM) of established specific transitions for 17-HDHA (343 245) and RvD1 (375 215). Identification was matching retention time and diagnostic ions to synthetic standards (14). B.