Humoral immunity: Primary response: The very first time the lymphocytes meet a particular antigen, plasma cells produce antibodies to kill the pathogen. Memory B cells remember how to kill the antigen. Secondary response: Exposure to the same antigen later triggers a stronger immune response, because the system is already prepared.
Cellular Immunity: T cells kill infected cells in the cell-mediated response. Once inside cells, pathogens are harder to detect. Cell-mediated immunity recognizes and kills the body’s own infected cells.
B-cells: Develop in the bone marrow and become antibody-producing plasma cells. Bind antigens to surface-bound antibodies.
T-cells: Develop in the thymus; differentiate into T-helper cells or T-cytotoxic cells.Antibodies: Antibodies are soluble proteins that are bound to the surface of cells, as well as unbound in the circulation. There are 5 types (isotypes) of antibodies: IgA: protects mucosal surfaces, IgD: B-Cell antigen receptor, IgE: involved in allergy, IgG: majority of antibody-based immunity and IgM: key to B-Cell immunity.