The Immune System

Antigens

Blood and the Lymphatic System

  1. Primary lymphoid tissues

    Thymus - behind the sternum; only active till puberty, releases thymosin which promotes the maturing of T cells → after puberty the gland shrinks and turns into fat; protects the body against autoimmunity;

  2. Secondary lymphoid tissues

Lymphocytes

  1. T cells (mature in the thymus)
  2. B cells (mature in bone marrow)
  3. NK cells

Phagocytes