B and T lymphocytes

B lymphocytes

Develop in bone marrow, produce antibodies.

T lymphocytes

Develop in thymus, provide cell-mediated immunity.

Stem cells

Give rise to lymphocyte precursors in bone marrow.

Humoral immunity

Antibody-mediated response to pathogens.

Cytokines

Chemical signals activating B and T cells.

Proliferation

Process of B cells making clones.

Differentiation

B cells develop into plasma or memory cells.

Antigen-presenting cell (APC)

Displays antigens to activate T cells.

Primary immune response

First encounter with antigen; takes 10 days.

Secondary immune response

Faster response upon re-encounter; takes 1 day.

Macrophage

Phagocytizes pathogens and presents antigens.

Helper T cells

Activate B cells and cytotoxic T cells.

Cytotoxic T cells

Directly attack and destroy infected cells.

Memory cells

Dormant cells that respond to future infections.

Immunoglobulins

Antibodies made of amino acids.

Monoclonal antibodies

Produced by fusing specific B cells with cancer cells.

Major Histocompatibility Complex (MHC)

Protein that presents antigens on cell surfaces.

Type I MHC

Found in all nucleated cells.

Type II MHC

Found in macrophages and B cells.

Agglutination

Clumping of antigens for easier phagocytosis.

Neutralization

Covers toxic parts of antigens, rendering them harmless.

Opsonization

Coats antigens with antibodies to enhance phagocytosis.

Chemotaxis

Attracts immune cells to sites of infection.

Inflammation

Response involving histamine release and increased blood flow.

Antigen-antibody complex

Formed when antibodies bind to antigens.