CS responses were elicited on day 4 after sensitization by painting both sides of the ears with 10 μl of 0.4% TNP-Cl in acetone and olive oil (1:1). Non-immunized controls were challenged identically. Ear thickness was measured with selleck kinase inhibitor a micrometre 1 day prior to challenge (baseline) and then 2 h (peak of the CS-initiating phase) and 24 h (peak of the CS-effector phase) following challenge. Ear swelling units were expressed in mm × 10−2. Each

bar represents the average response ±SE in a group of four mice. Hepatic lipid extraction from contact-sensitized mice.  Wild-type BALB/c mice were contact-sensitized or sham-sensitized as described earlier. Thirty minutes later, mice were killed by cervical dislocation. Livers were isolated and placed in 2 ml of water on ice for several minutes to allow for hypotonic cell lysis before homogenization with tissue tearor at 17 000 rpm for 1 min. Samples were then sonicated while on ice for 1–2 min. Lipids were subsequently isolated from the lysate by two serial cycles of chloroform and methanol extraction (10 volumes each per gram of tissue per cycle; incubations were 12 h followed by 4 h, each at 4 °C). We recognize that the extracts we obtained also contained

DNA and RNA, but herein for convenience we refer to them as ‘lipid extracts. Isolation of iNKT cell-containing liver mononuclear cells (LMNC).  Liver mononuclear cells isolation was performed as described previously [9]. LMNC were obtained from wild-type BALB/c mice Cyclooxygenase (COX) except as otherwise indicated in the text. Viability HDAC inhibitor was >90%, and ∼0.5−1 × 106 LMNC were obtained per mouse. iNKT cells constitute approximately 70% of wild-type LMNC; hepatic iNKT cells have previously been shown to play a key role in CS [9]. For simplicity, iNKT cell-containing LMNC will be referred to as ‘iNKT cells’ in the text. In vitro treatment of iNKT cells with lipid extracts.  Naïve wild-type iNKT

cell-containing LMNC were incubated in vitro with α-GalCer or hepatic lipid extracts from wild-type mice (after either contact sensitization or sham sensitization), with or without anti-CD1d antibody (at a concentration of 10 μg/ml for 1 h at 37 °C). Lipid donors and LMNC donors were age-, sex- and size-matched. The ratio of number of lipid donors to number of LMNC donors was 1:1 in incubations. Isolation of peritoneal B-1 B cells.  Peritoneal cells of wild-type CBA/J were harvested by lavage with 4 ml of cold 1% foetal bovine serum (Gibco BRL, Carlsbad, CA, USA) containing heparin (10 U/ml; Sigma) in PBS, washed three times and resuspended in RPMI 1640 containing 10% FBS, 25 mm Hepes, 100 units/ml penicillin and 100 μg/ml streptomycin; 5 × 106 peritoneal cells were obtained per mouse. Peritoneal cells contain approximately 20% B-1 B cells; the vast majority of murine B-1 B cells reside in the peritoneum.