IMAGE (IMAGE) Nara Institute of Science and Technology Caption Influenza virus-specific CD8+ T cells induced in lymph nodes as a result of influenza virus infection or vaccination circulate throughout the body. During second influenza virus infection, viral fragments taken up by alveolar macrophages (AMs) are presented as antigens to promote virus-specific CD8+ T cells proliferation. The proliferated CD8+ T cells suppress viral proliferation. In addition, interleukin-18 (IL-18) released from AMs induces resident memory type CD8+ T cells, contributing to long-term host defense. Credit Takumi Kawasaki and Taro Kawai Usage Restrictions Credit required License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.