1) Macrophages ingest antigen 2) Helper T cells are activated 3) B cells differentiate into plasma cells and memory cells.
Explanation:
Innate immunity and adaptive immunity provide protection against foreign invaders. Innate immunity is non specific and adaptive immunity is specific immune response; includes the production of antibody after a sequence of events.
When an antigen enters the body the phagocytic cells such as macrophages and dendritic cells ingest the antigen by a process called as phagocytosis. These cells act as antigen presenting cells and present it to T cells.
T cells are of two types T helper cells and T cytotoxic cell. T cytotoxic cells killed the affected cell such as affected by virus while T helper cells signal for the production antibodies.
Antibodies are produced from the plasma cells while memory cells act as record keeping. The plasma cells are stimulated by interleukins.