Objectives - To evaluate the effects of equine sCD14 and monoclonal antibodies (mAbs) to equine CD14 on LPS-induced TNF° expression of equine peripheral blood mononuclear cells (PBMCs). To determine serum concentrations of soluble (sCD14) in a population of horses with gastrointestinal diseases or other illnesses likely to result in endotoxemia; and identify relationships with clinical data.

Animals - Part 1; 10 healthy horses. Part 2; 55 clinical cases and 23 healthy control horses.

Procedure - Part 1; PBMCs were incubated with Escherichia coli LPS, CD14 mAb, sCD14, CD14 mAb plus E coli LPS or sCD14 plus E coli LPS. Supernatants were collected at 6 hours and assayed for tumor necrosis factor ° (TNF°) activity. Part 2; Serum sCD14 was measured at admission and then at 24 and 48 hours after admission using a bead-based multiplex assay.

Results - Part 1; Pre-incubation with CD14 mAb did not inhibit LPS-induced TNF° protein production in isolated equine monocytes. Use of sCD14 inhibited LPS-induced TNF° protein production in isolated monocytes in a concentration-dependent manner. Part 2; Serum concentration of sCD14 was positively related to duration of clinical signs (P = 0.007), respiratory rate (P=0.04) and band neutrophil count (P = 0.0002). There was no correlation between serum concentration of sCD14 and heart rate, temperature, hematocrit, lactate, white blood cell count, fibrinogen, creatinine, urea nitrogen, glucose and anion gap values. Serum sCD14 did not correlate with outcome at any time point for clinical cases.