Production of cytotoxic factor in the spleen of dengue virus-infected mice.

Swiss albino mice inoculated i.c. with dengue type 2 virus (DV) show presence of a factor in the spleen which is cytotoxic to the normal mice spleen cells in vitro. The cytotoxic factor is present in the homogenate as well as in the culture supernatants of the spleen cells. Maximum cytotoxic activity is present in the spleen of moribund mice on 10-11 p.i. day. No cytotoxic activity was found in the homogenates of brain, liver, heart and skeletal muscles. Sera from a few mice only had cytotoxic activity and were not complement-dependent. Cytotoxic activity in the homogenate and culture supernatant (TCF) of various spleen cell populations was screened. Cytotoxicity of glass-non-adherent cells was significantly higher. DV-infected spleen cells, depleted of macrophages by carbonyl iron treatment, had higher cytotoxic activity. B-cell-enriched fractions and the glass-adherent cells had negligible cytotoxic activity. Purified lymphocytes and the T-lymphocyte-enriched fractions had maximum cytotoxicity. Thus, a cytotoxic factor is produced by T lymphocytes of the spleen of DV-infected mice which kills normal mouse spleen cells in vitro.