Production of random classes of immunoglobulins in brain tissue during persistent viral infection paralleled by secretion of interleukin-6 (IL-6) but not IL-4, IL-5, and gamma interferon

The activities of cytokines were determined in cerebrospinal fluid (CSF) and serum of mice persistently or intracerebrally acutely infected with lymphocytic choriomeningitis (LCM) virus (LCMV). In contrast to CBA/J (LCMV carrier) mice that responded with low levels of LCMV-specific antibody, high-responder NMRI (carrier) mice showed antibody production by B cells outside of lymphoid organs. The B cells that had infiltrated the brains of LCMV carrier mice exhihited no preferential immunoglobulin isotype or subtype virus-specific antibody production. Phenotypic analysis of the brain infiltrates in virus carrier mice revealed dominance of CD4⁺ T cells in contrast to virtual absence of CD4⁺ and dominance of CD8⁺ in mice with acute LCM. In NMRI but not in CBA/J carrier mice, significant concentrations of interleukin-6 (IL-6) were detected in CSF and serum; IL-2, IL-4, IL-5, granulocyte-macrophage CSF (GM-CSF), and gamma interferon (IFN-γ) were not elevated. In contrast, during acute, lethal LCM, IL-6 and IFN-γ were found at high concentrations, and IL-4, IL-5, and GM-CSF were detectable in CSF and serum, but virus-speciflc antibody-producing cells were not (yet) detectable in the brain. Thus, distinct cytokine patterns are found in acute versus chronic LCMV infection of the brain: in LCM carrier mice, local random-class immunoglobulin production correlated with the absence of IL-2, IL-4, IL-5, and IFN-γ but active secretion of IL-6.