Clonal expansion and functional analysis of virus-specific T lymphocytes from cerebrospinal fluid in measles encephalitis.

T cells were directly cloned from the cerebrospinal fluid (CSF) of a patient with acute measles encephalitis by limiting dilution in the presence of irradiated feeder cells and T cell growth factor (TCGF). A total of 42 colonies was established. Functional analysis revealed 27 of them to be derived from a cytotoxic T lymphocyte as demonstrated by the ability to exert phytohaemagglutinin (PHA)-dependent cytotoxicity against uninfected allogeneic PHA blasts. Twenty-three of the cytotoxic colonies were specific for measles virus and restricted to self HLA-A or -B antigens. Three clones were also found to give measles virus-specific proliferative responses. The results show that the CSF in measles encephalitis contains a highly enriched population of in vivo sensitized antigen-specific T cells. We propose that the clinical symptoms in measles encephalitis are caused by a T cell-mediated reaction against virus-infected brain cells.