Barriers and early responses
Skin and mucosal barriers limit entry, while innate cells and molecules recognize shared features and organize early responses. Inflammation recruits cells and changes local conditions in connection with repair. These broad recognition systems act before a particular antibody response develops and help establish conditions for subsequent immune activity.
References: [2]
Specificity and memory
Adaptive immunity involves B and T cells recognizing particular targets. Relevant cells expand and differentiate, with some becoming memory cells that change responses on later encounters. Antibodies are important products, but cell-mediated responses also perform essential tasks. Antibody quantity alone does not summarize the complete immune response.
References: [3]
Active and passive acquisition
Infection or vaccination can induce a recipient’s own adaptive response. Passive immunity instead supplies existing antibodies, including some maternal transfers and antibody products. Receiving antibodies differs from developing one’s own memory in mechanism and persistence. Serum treatment and vaccination are historically related approaches built on distinct biological processes.
Defence requires regulation
Immune activity involves many cells, tissues and signals, with targets, location and intensity regulated together. Barriers, antibodies, phagocytosis and other cellular processes cooperate under particular pathogen and host conditions. Research examines coordination, the development of protection and its changes rather than reducing all defences to a single scale of strength.