Lecture 4 Flashcards
What are manual WBC counts used for?
Mainly used in today’s modern lab for CSF , sperm count, peri –cardial, synovial and pleural count.
Describe WBC
- approx 10-20 µm diameter (2-3 x size of RBC)
- can count under 400 x magnification (high dry)
- can see detail under 1000 x magnification (oil immersion)
- cells are nucleated,
- flexible membrane with variable shape, resists lysis
Lymphocytes
Bcells - antibody production
T cells - T helper and T cytotoxic
25-33% of wbcs
only a little larger than wbcs. the nucleus almost fills the whole cell leaves a little sliver of cytoplasm
provides immunity
Neutrophils
Phagocytic against bacteria coated with antibody
Receptors specific for bacteria
Kill with Lysosomes
they are 60% of WBC
Nucleus with three to five lobes and have phagocytic qualities
Destruction of bacteria and their numbers increase in the early stage of acute inflammation.
stains light purple in acid and base stains
Eosinophils
Attracted to the site of allergy
IgE receptors
Granules with allergic response (not histamiine)
(3%) of WBCs
Fight parasitic infections and are also increased in number in people with acute or active allergies
nucleus is bilobed- stain red in acid stain
Basophils
Contain vacoactive amines, histamine and serotonin
<1% of WBCs
Release substances such as histamine, which promotes inflammation
Release heparin, which is an anticoagulant and histamine
nucleus is lobed takes up the whole cell, stains blue in basic stain
Monocytes
phagocytic and present bacterial antigen to T helper cells
8% of wbcs - very big
Agranulocytes - very fine granules
Active and quite large (macrophages) when they leave the blood vessel and enter tissues
2-3 times larger than RBC. Nucleus can be spherical or lobed.
phagocytizes large particles and old RBC
bean shaped
What happens at the beginning of a bacterial infection or acute inflammation?
Number of neutrophils increases
What happens 2 weeks after a bacterial infection?
Monocytes increase
What happens during a parasitic infection
Eosinophil numbers increase
What happens in viral infections and chronic illness?
Lymphocytes increase
What happens in a person with AIDS
T Lymphocytes decrease
What happens during allergic reactions?
Basophils increase
Principle of manual count
- dilute EDTA blood with fluid that lyses RBCs and stains WBCs
- count the WBCs in a known volume of blood
- calculate cells/L
Dilution factor
• Dilute blood 1/100 (1.98ml diluent +in 0.02ml blood) – count all 9 squares
• 1/20 (180 ul diluents + 20 ul blood) – count 4 large squares
• Diluent -2% - 3% acetic acid (CH3COOH) with dye
count with neubauer hemocytometer
= 20