Brief Definitive Report MACROPHAGES GENETICALLY RESISTANT TO MOUSE HEPATITIS VIRUS CONVERTED IN VITRO TO SUSCEPTIBLE MACROPHAGES* BY W. WEISER AND F. B. BANG

Genetically resistant C3H mice have been made phenotypically susceptible to mouse hepatitis virus (MHV) by cortisone (1), cytoxan (2), and eperythrozoon infection (3). There is extensive evidence that cultured macrophages from genetically resistant or susceptible strains of mice reflect the genetic resistance or susceptibility of the host. Yet the effects of cortisone, cytoxan, and epierythrozoon in vitro are minimal or absent. However, experiments reported here have shown that certain substances (lymphokines) in supernatant fluid from allogeneic mixed lymphocyte cultures (MLC) rendered the macrophages of C3H mice susceptible to MHV. Fluid derived from congenic MLC did not change the resistance of C3H macrophages to the virus.