Normal Values. The normal percentages of the different leukocytes are:
Eosinophils (Eos) 2-4 percent
Basophils (Bases) 0-2 percent
Lymphocytes (Lymphs) 21-35 percent
Monocytes (Monos) 4-8 percent
Metamyelocytes (Metas) 0 percent
Bands or Stab forms (Bands) 0-10 percent
Segmented (Segs or 51-67percent Polys)
Most hospital corpsmen have heard the expression shift to the left and shift to the right. These terms are often loosely used in referring to an increase in bands or an increase in segs, respectively. The true meaning of the terms can best be explained by the following diagram:
The metamyelocytes, bands, and segmented neutrophils constitute the neutrophilic cells. When the cells to the left of the segs are increases, it is a shift to the left. If the segmented neutrophils increase, it is a shift to the right. The true right shift will show numerous hypersegmented (having six or more lobes) neutrophils.
The severity of an infection maybe determined total white cell count and the differential by the count.
Leukocytosis (abnormally high white cell count) with an increase in the percentage of neutrophil indicates a severe infection with a good response of the bone marrow. The primary phagocytes (bacteria-destroying cells) are the neutrophils, and the bone marrow should supply large numbers of these to combat the infection. The greater the shift to the left (increase in immature neutrophils), the more severe the infection. The appearance of numerous juvenile cells (metamyelocytes) indicates irritation of the bone marrow with regeneration. If the infection continues and the patients resistance declines, the shift advances further to the left. If improvement ensues, the shift declines and recedes to normal.
A falling white cell count with the number and maturity of neutrophils progressing toward normal indicates recovery.
A continued shift to the left with a falling total white cell count indicates a breakdown of the bodys defense mechanism and is a poor prognosis.
The percentage of eosinophils, lymphocytes, and monocytes generally decreases in acute infections.
In tuberculosis an increase in monocytes (monocytosis) indicates activity in the infected area. An increase in lymphocytes (lymphocytosis) indicates healing.
Eosinophils increase in parasitic infections and allergic conditions.
Four plain glass microscope slides, clean and dry.
Wrights stain, powder or tablet form. Prepare this stain as follows.
Tablets: Use one tablet for each 10 ml of reagent grade methyl alcohol. Dissolve tablets after crushing them with the aid of a clean, dry mortar and pestle. Pour the solution in a stopper bottle and store for 30 days in a dark place, shaking it periodically during this period. Filter before use. Fill a dropper bottle for use at the lab bench.