Which of the following are entities involved with the body’s immunity?

Entities involved with the body's immunity include:

1. Immune cells: These are specialized cells that recognize and respond to foreign substances. They include white blood cells such as lymphocytes (T-cells and B-cells), macrophages, neutrophils, natural killer cells, and dendritic cells. 2. Antibodies: Also known as immunoglobulins, these are proteins produced by B-cells that can specifically recognize and bind to foreign substances called antigens.

3. The complement system: This is a group of proteins that work with antibodies to destroy pathogens or mark them for destruction by other cells.

4. Lymphoid tissues: This includes the lymph nodes, spleen, thymus, and tonsils which are sites where immune cells are stored, mature, or are activated.

5. Bone marrow: The soft tissue in the bones where all blood cells, including immune cells, are originated from stem cells.

6. Physical barriers: Though not entities per se, physical barriers such as the skin and mucous membranes act as the first line of defense to block the entry of pathogens.

This complex interplay of cells, tissues, and molecules forms the immune system, which defends against infections and diseases.