If the neutrophil count was high in a WBC differential, what kind of infection would you suspect? If the lymphocyte count was high?

WBC differential is a blood test that measures each type of leukocyte present in a specimen. The total WBC for children over 2 years to adult is 5,000 - 10,000/mm3, for children under 2 years 6,200 - 17,000, for a newborn 9,000 - 30,000 (Pagana & Pagana, 2003). Leukocytes are white blood cells that “defend the body against organisms that cause infection and remove debris, including dead or injured host cells of all kinds” (McCance & Heuther, 2006 p.896). Neutrophils and lymphocytes make up 75-90 % of total leukocytes. Leukocytes structures are either granulocytes or agranulocytes and they function as phagocytes or immunocytes. Granulocytes consist of membrane bound granules in their cytoplasm. These granules contain enzymes capable of killing micro-organisms and catabolizing debris ingested during phagocytosis Phagocytes encapsulate and consume foreign micro-organisms and cellar debris (McCance & Heuther, 2006).

Neutrophils are classified as granulocytes and function as phagocytes, along with basophiles and eosinophils. Neutrophils are bacteria killing cells that are activated in the early stages of inflammation, about 6 to 12 hours after the initial injury. They migrate out of the capillaries and into the inflamed site. At the siteof infection they ingest and destroy the micro-organisms and debris and cell death occurs within 1-2 days. Dead Neutrophils release digestive enzymes from the cytoplasm granules. This process prepares the site for healing (McCance & Heuther, 2006). When neutrophil production is significantly stimulated, early immature forms of neutrophils enter the circulation (band or stab cells) and this is called a “shift to the left”. The normal neutrophil value is 2,500 - 8,000/mm3 and a high count is indicative of an ongoing acute bacterial infection. (Pagana & Pagana, 2003)

Lymphocytes stem from bone marrow and the thymus. The thymus releases T cells, and the bone marrow releases B cells which are the two types of lymphocytes. The T cells serve functions such as killer cells, memory cells, and regulatory cells. The killer cells attack and kill targeted cells infected with abnormal DNA or RNA, such as those with a viral invasion. The memory cell's purpose is to remember a specific antigen. In the event of reinvasion, a prompt and specific immune response would occur. The regulatory T cells help control the immune response so that over activation is avoided, and self antigens are not attacked. B cells serve as memory cells, and present the antigen to the T cells to facilitate a humoral immune response. B cells also specialize to produce specific antibodies to fight infection (McCance, K. & Heuther, S., 2006). The normal lab values for lymphocytes are 1,000 - 4,000/mm3 (Pagana & Pagana, 2003).

If the lymphocyte count was high in a WBC count differential, it might be considered to be a chronic infection, or a recurrent infection. The infection could be viral, bacterial, or parasitic, and to differentiate between them, testing of immunoglobulin’s may be warranted. If the neutrophil count was high in a WBC differential, an acute bacterial infection could be suspected.

Virginia, Kelly Anne, Krista, Bambi and Deanna (Group B)

References

McCance, K. (2006). Stucture and Function of the Hematologic System. K.L. McCance and S.E. Heuther (Eds.), Pathophysiology: The biologic Basis for Disease in Adults and Childern (pp. 896- 898).St.Louis, Missouri: Elsevier.

Pagana, K., and Pagana, T. (2003). Mosby's Diagnostic and labratory Test Reference (6th ED). St. Louis, Missouri: Elsevier.