While all of the cells listed may have some indirect involvement in the overall response to a parasitic infection, eosinophils are the only immune cells that are specialized to respond to multicellular parasites, especially helminths such as hookworms and pinworms.

Mast cells are rich in granules that contain high concentrations of heparin, histamine, and trypsin, among other preformed proteases. These granules also contain serotonin and various eicosanoids. The function of mast cells is primarily to regulate immune (inflammatory) responses to allergens.

Macrophages, the main blood cells responsible for phagocytosis of debris, bacteria, and virally infected cells, are part of the nonspecific immune response. While they are able to recognize self versus non-self proteins, they are not uniquely sensitive to any particular non-self protein type. Rathe, they phagocytose foreign matter as well as cellular debris. Plasma cells, memory cells, and CD8 T cells are all lymphocytes, and as such they are all part of the adaptive or "specific" immune system, meaning that they are uniquely sensitive to particular pathogenic proteins.

Lysozymes are a group of defense enzymes found in tears, saliva, mucus, and breast milk. It is considered part of our innate immune systems, as its presence in tears prevents infectious conjunctivitis. Cathelicidin, Defensin-5, and DEFA1 are found in the lysosomes of polymorphonuclear leukocytes (PMN's) and macrophages.

While all of the enzymes listed are present in saliva, lysozyme is the only enzyme listed that has antibacterial properties. This enzyme, present not only in saliva but also in tears, sweat, and breast milk, damages bacterial cell walls, making it an important part of the innate immune system. Amylase breaks down carbohydrates, lipase breaks down lipids, and kallikrein breaks down proteins.

Interleukins (IL) are cytokines that play a role in signaling the immune cells. IL-8 is produced mainly by macrophage and dendritic cells and plays a major role in inflammation as a chemoattractant for neutrophils. IL-1 and IL-6 both induce acute phase proteins. TNF-alpha is involved in the acute phase reaction. It is an endogenous pyrogen (meaning it induces fever) and is also involved in apoptosis and tumor inhibition.

T lymphocytes are so titled because they mature in the thymus, unlike B lymphocytes, which mature in the bone marrow. The thymus is located in the anterior superior mediastinum, ventral to the heart and dorsal to the sternum. It is most active in the neonatal and pre-adolescent periods, afterwards, it degenerates and is replaced with adipose tissue.

Antibodies are only produced by B cells, specifically by a type of specialized B cell called a plasma cell. B cells belong to a broader category of leukocytes known as lymphocytes, which are agranulocytes.

Major histocompatibility complex 1 in a membrane protein that binds to peptide fragments from pathogens such as viruses and bacteria and then displays them on the cell surface in order to alert other immune cells of the presence and nature of infection.

All cells with nuclei express MHC-1. Red blood cells do not have nuclei, and do not express MHC-1 on membranes.

Lymphoid progenitor cells are produced in all of the following tissues: the liver, the bone marrow, spleen, and gut associated lymphoid tissue (mainly found in the liver and intestines). However, note that the vast majority of all blood cells are produced in the red bone marrow of long bones by hematopoietic stem cells.