Antigen-specific T-cell responses during primary and secondary Listeria monocytogenes infection

Although murine listeriosis is a widely used experimental model for the analysis of cell-mediated immunity, there is little information about individual T-cell antigens of Listeria monocytogenes which are recognized during primary and secondary infection. To study the antigen responses of L. monocytogenes-reactive T cells, somatic and secreted listerial proteins were separated by two-dimensional gel electrophoresis and subsequently divided into 480 liquid fractions. Antigen-specific T cells isolated from mice at different times of primary and secondary listeriosis were tested for their capacity to proliferate with distinct protein fractions. Supernatants of these cultures were screened for the production of gamma interferon, interleukin-4 (IL-4), and IL-10. Proliferation of antigen-specific T cells correlated with the production of high concentrations of gamma interferon, whereas IL-4 and IL-10 production in response to listerial protein fractions could not be detected. During both primary and secondary listeriosis, T cells recognized a multitude of somatic and secreted proteins rather than one or a few dominant antigens. Secreted proteins were recognized before somatic proteins, and T cells recognized different fractions in secreted and somatic proteins.