Role of CD16 in Immune Response

B Cells

• Pro-B cells have distinct markers: CD19, CD45R, CD43, CD24, and c-Kit.
• Pre-B cells are characterized by immunoglobulin gene arrangement and the appearance of heavy chains in the cytoplasm.
• Immature B cells have light chain genes rearranged, and light chains appear in the cytoplasm, forming IgM when coupled with heavy chains.
• Mature B cells exhibit IgD on their surface, along with IgM.
• Activated B cells exhibit markers like CD25, which is a receptor for IL-2, and transform into blasts that give rise to plasma cells and memory cells.

Natural Killer Cells (NK Cells)

• CD16 is a receptor for the Fc portion of IgG, allowing NK cells to attach to and lyse cells coated with antibody.
• CD56 mediates interactions between effector and target cells.

LAK Cells and K Cells

• LAK cells are lymphokine-activated killer cells that use IL-2 to help lyse tumor cells.
• K cells express surface immunoglobulin receptors and lyse target cells by ADCC (Antibody-Dependent Cellular Cytotoxicity).

Macrophages

• Phagocytic cells that act nonspecifically, ingesting and destroying bacteria, damaged host cells, or tumor cells.
• Macrophages "process" antigen (as do T lymphocytes) before presentation to B lymphocytes.
• Destroy target cells by phagocytosis (in lymph nodes and spleen) and direct cytotoxic effects on antibody-coated cells.

Secondary Lymphoid Organs

• Main function: filtration, where lymph fluid flows slowly through spaces called sinuses, lined with macrophages, creating an ideal location for phagocytosis.

Other Lymphoid Organs

• MALT (Mucosal Associated Lymphoid Tissue) includes gastrointestinal, respiratory, and urogenital tracts.
• MALT is important for immunoglobulin A production and development of tolerance to ingested antigens.
• Peyer's patches are a specialized type of MALT located at the lower ileum of the intestinal tract.

Surface Markers on Lymphocytes

• Proteins that appear on cell surfaces can be used as markers to differentiate T cells and B cells.
• Proteins can also be used to distinguish the developmental stages of the two types of cells according to when they appear.

Cells of the Immune System

• T cells are the chief lymphocytes in blood and lymph, have a long life span, and are thymus-dependent.
• Double negative stage: early thymocytes lack CD4 and CD8 markers.

Learn about how CD16 plays a crucial role in bridging the innate and acquired immune responses to various pathogens and target cells, including tumor cells, embryonic cells, bone marrow cells, thymus cells, and microbial antigens.