IL-4 induced CD23 (FcepsilonRII) up-regulation in equine peripheral blood mononuclear cells and pulmonary alveolar macrophages.

Abstract

The objectives of this study were to quantify the induction of equine CD23 transcripts in equine peripheral blood mononuclear cells (PBMCs) and pulmonary alveolar macrophages cultured with recombinant equine IL-4 (rEq IL-4). PBMCs were isolated from blood drawn from four healthy horses. Bronchoalveolar lavage (BAL) fluid was collected from three healthy horses and alveolar macrophages were purified using adherence to plastic for 120 min. PBMCs and alveolar macrophages were cultured using four different conditions: rEq IL-4 and LPS, LPS alone, rEq IL-4 alone and a media control. Total RNA was isolated from cells cultured for 24 or 48 h. Reverse transcribed mRNA was amplified and quantified in real-time polymerase chain reaction (RT PCR) using a fluorescein labeled internal TaqMan probe for CD23 expression. Without exception, the relative value for CD23 mRNA transcripts from equine PBMCs and pulmonary alveolar macrophages cultured with rEq IL-4 for 24 and 48 h were higher than those cultured with LPS alone or the untreated control. Furthermore, morphologic changes were noted in alveolar macrophages cultured with rEq IL-4 prompting an investigation of cytokine expression levels. Alveolar macrophages cultured with LPS exhibited increased IL-8 and IL-12 p40 expression when compared to rEq IL-4, rEq IL-4 + LPS or the untreated control. These findings support two conclusions, (1) equine CD23 has a role in IL-4 mediated immune responses in the horse and (2) rEq IL-4 can modulate LPS-induced, pro-inflammatory cytokine production by equine pulmonary alveolar macrophages.