Induction of Apoptosis Reduces Immunogenicity of Human T‐Cell Lines in Mice

Abstract

Apoptotic cells, e.g. postinflammatory neutrophils, were reported to be engulfed by phagocytes without induction of an inflammatory response. We investigated the humoral immune response of BALB/c mice after repeated injection of viable or apoptotic human T cells. Following interleukin‐2 (IL‐2) deprivation, phytohaemagglutinin (PHA)/IL‐2 expanded human T‐cell lines were irradiated with UV‐B light to induce apoptosis, confirmed by propidium iodide staining of Triton X‐100‐lysed cells. Indirect immunofluorescence was used to detect antilymphocyte antibodies 7 days after each injection. We found high levels of antilymphocyte antibodies in all animals immunized with viable T cells, whereas animals injected with apoptotic cells showed a significantly reduced humoral immune response. We conclude that apoptotic cells induce poor xenoreactive T‐cell responses when compared with viable cells.