Interactions of murine leukemia virus (MuLV) with isolated lymphocytes. I. Virus replication in lymphocytes infected with Friend virus and cultures in diffusion chambers in vivo.

A new technique for infection of mature lymphocytes with murine leukemia virus (Friend) MuLV-F) is described. Spleen cells for normal, non-infected donors were placed into diffusion chambers (constructed with 0.22 mum por size Millipore filters) which were then implanted into the peritoneal cavities of normal syngeneic recipient mice. The cells were infected with an injection of MuLV-F into the peritoneal cavity and, in some instances, also by placing virus into the chambers. Cells were recovered by treating the chamber content with elastase and collagenase. The infection was determined in two ways: (1) cells with replicating MuLV were enumerated as infection centers (IC) on S+L- indicator cells; and (2) virus-related cell membrane antigen (MA) was detected by immunofluorescence. Cells recovered from chambers after 2-3 weeks of culture represented about 10% of the original inoculum; viability was approximately 90%. The number of IC in MuLV-F-infected chambers was about 10 times higher than obtained by infection and cultivation of spleen cells in vitro. The kinetics of IC and MA in chamber-cultured. MuLV-F-infected spleen cells was similar to that in the spleen of infected mice during the first 10 days after infection. Later on, the process of infection within the chambers slowed down, reaching about 50% MA-positive and about 10% IC-positive cells, whereas the number of both IC- and MA-positive cells in the spleen reached 80% or more. The infection of splenic lymphocytes in diffusion chambers occurred equally well when chambers were implanted into: (1) syngeneic, virus susceptible hosts; (2) syngeneic, lethally irradiated hosts; and (3) allogeneic, virus-resistant hosts, suggesting that the process within the chamber is independent of MuLV replication in the tissues of the chamber-bearing mouse. The diffusion chamber technique seems to provide an environment in which various types of isolated lymphocytes of different mouse strains can interact with MuLV almost as efficiently as in vivo.