Expression of macrophage CD44 receptor in the course of experimental inflammatory response of bovine mammary gland induced by lipopolysaccharide and muramyl dipeptide.

The aim of this study was to investigate development over time of the surface expression of CD44 on macrophages during an inflammatory response of bovine mammary gland. Intramammary instillation of muramyl dipeptide (MDP) and lipopolysaccharide (LPS) resulted in a significant increase in the total count of CD44+ non-vacuolised macrophages ((N)MAC) after 24h. During resolution of the inflammatory response, there was observed a gradual decrease in the total count CD44+ (N)MAC. The lower total count and proportion of CD44+vacuolised macrophages ((V)MAC) was observed as the effect of MDP and LPS at 24h after induction (P<0.01). During resolution, the total count and proportion of CD44+(V)MAC increased. We have demonstrated CD44 receptor is expressed during the inflammatory response caused by LPS and MDP and the effect of these components on CD44 expression was particularly evident during initiation of the inflammatory response. High expression of CD44 in resolution of inflammatory response may relate to macrophages involvement in the processes leading to restitution of injured tissues.