“…While MDP has been shown to stimulate guinea pig peritoneal exudate macrophages in vitro without the involvement of lymphocytes (33)(34)(35)52), there are conflicting reports in the literature on the stimulation of murine macrophages by MDP. Some investigators have, on the basis of in vitro assay results, reported that murine macrophages are the initial target cells of MDP (11,16,18,38,48,49,51), while others have failed to show in vitro activation of murine macrophages by MDP (30,45,53).…”