Neutrophils are the first type of immune cell to respond to and arrive at the site of infection, often within an hour. Neutrophils will respond to infection inside the body, but also on the surface, as in the case of skin infections. Pus, which is one visible sign of a skin infection, contains mainly dead neutrophils, bacteria, and cells. Pus can form internally, as well.
The results of a common blood test, called an absolute neutrophil count (ANC), are routinely checked during cancer treatment to determine how the immune system is responding to treatment. When ANC is low, this is called neutropenia. If ANC drops below about 500 cells per microliter, the risk of infection increases and your doctor may prescribe medications to bring ANC back into a normal range and temporarily offer antibiotics to prevent serious infections.
Neutrophils are part of the innate immune system, which means that they can "non-specifically" destroy any invaders that they encounter in the body, such as bacteria and parasites. Non-specifically means that neutrophils do not have to recognize the invader specifically, but instead simply recognize the invader as something that should not be present in the body and should be destroyed.
Eosinophil granulocytes, usually called eosinophils or eosinophiles (or, less commonly, acidophils), are white blood cells that are one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. Along with mast cells, they also control mechanisms associated with allergy and asthma. They are granulocytes that develop during haematopoiesis in the bone marrow before migrating into blood.
These cells are eosinophilic or 'acid-loving' as shown by their affinity to coal and tar dyes: Normally transparent, it is this affinity that causes them to appear brick-red after staining with eosin, a red dye, using the Romanowsky method. The staining is concentrated in small granules within the cellular cytoplasm, which contain many chemical mediators, such as histamines and proteins such as eosinophil peroxidase, ribonuclease (RNase), deoxyribonucleases, lipase, plasminogen, and major basic protein. These mediators are released by a process called degranulation following activation of the eosinophil, and are toxic to both parasite and host tissues.
Basophil granulocytes, sometimes referred to as basophils, are the least common of the granulocytes, representing about 0.01% to 0.3% of circulating white blood cells.
The name comes from the fact that these leukocytes are basophilic, i.e., they are susceptible to staining by basic dyes, as shown in the picture.
Basophils contain large cytoplasmic granules which obscure the cell nucleus under the microscope. However, when unstained, the nucleus is visible and it usually has 2 lobes. The mast cell, a cell in tissues, has many similar characteristics. For example, both cell types store histamine, a chemical that is secreted by the cells when stimulated in certain ways (histamine causes some of the symptoms of an allergic reaction). Like all circulating granulocytes, basophils can be recruited out of the blood into a tissue when needed.
monocytes,n.pl the largest of the white blood cells. They have one nucleus and a large amount of grayish-blue cytoplasm. Develop into macrophages and both consume foreign material and alert T cells to its presence.
LEARN MORE ABOUT MONOCYTES: Monocytes(biology)-- Britannica
lymphocyte, Human lymphocyte (phase-contrast microphotograph). [Credit: Manfred Kage/Peter Arnold]type of leukocyte (white blood cell) that is of fundamental importance in the immune system because lymphocytes are the cells that determine the specificity of the immune response to infectious microorganisms and other foreign substances. In humans lymphocytes make up 25 to 33 percent of the total number of leukocytes. They are found in the circulation and also are concentrated in central lymphoid organs and tissues, such as the spleen, tonsils, and lymph nodes, where the initial immune response is likely to occur.
CLICK LINK FOR MORE GREAT NOTES ON BLOOD (INCLUDING WHITE BLOOD CELLS EXPLAINED ABOVE): Blood