Many of the immune cells are involved to protect the body against the specific microbes and thus inhibiting their chemicals by binding to the specific surfaces of pathogens. Human body has different cells particularly important in defending the body against the pathogens. Different cells are involved in protecting the body as part of innate immunity. This innate immunity includes the external barriers of the body as the first line of defense against pathogens such as the skin. Molecules on the pathogens surface may be recognized directly by the PRRs of resident macrophage. Natural killer cells also involved in immune response by killing the cancerous cells or viral proteins by attaching on their surface. The main mechanism of the innate immune response to eradicate bacteria is activation of the complement system, phagocytosis, and inflammatory response. Listeria monocytogenes is the pathogenic form of bacterial species that causes disease transmitted through the infected foods. Interferons tightly bind to the viral proteins and inhibit their production. Different vaccines have been used to treat the number of diseases and each vaccine works for against the specific diseases in order to make the immunity.