A METHOD FOR ISOLATION AND PARTIAL-PURIFICATION OF TRICHINELLA-SPIRALIS NURSE CELLS

Invasion of vertebrate muscle cells by larvae of Trichinella spiralis is accompanied by redifferentiation of the host myofiber into a novel structure called the nurse cell. The nurse cell protects and nurtures the enclosed parasite during its long stay in host muscle. It is anato mically independent of the surrounding uninfected muscle cells and can be isolated from host tissue by mechanical or enzymatic means. Curren t methods employed for this purpose have yielded only small numbers of nurse cells. An apparatus designed to isolate large numbers of nurse cells and a method for removal of all free larvae and most host muscle debris is described. Homogenization and trypsin digestion of muscle t issue was followed by passage of muscle/parasite suspensions maintaine d at 37 C through a jacketed glass column fitted with a 40-mesh stainl ess steel screen at the top and a Nitex screen with 150-mu m-diameter pores at the bottom. Nurse cells were retained by the Nitex screen. De nsity gradient centrifugation using Percoll removed all free larvae an d most contaminating muscle debris from nurse cell suspensions. The la rge quantities of nurse cells made available by this method will allow evaluation of the molecular biology, nutrition, biochemistry, and met abolism of the enclosed parasite and of the Trichinella-modified host muscle cell.