reduce allergic inflam. by producing enzymes that inactivate vasoactive subst.from basophils and mast cells
Basophils
—less than 1% of WBC, 12um
nucleus 2-lobed or irregular, occupies a large portion of the cell
cytoplasm contains specific granules (histamine and other vasoactive substances) dark-purple with basic dye
similar but not identical to mast cells (in tissue)—both produce allergic inflammatory response
immunoglobin E binding to surface + interaction with specific antigen Þ
release vasoactive mediators
Lymphocytes
—20-40% of WBC, small (6-10um), medium (10-12um), large (12-15um) (most small or medium)
nucleus round or oval with slight indentation, occupies a large part of the cell—moderately dense chomatin
cytoplasm sparse (more in larger) with free ribosomes (basophilic) and occasional azure granules
immunological defense mechanism—circulate between lymphoid organs and body tissues
two types (indistinguishable here, but can be distinguished with immunocytochemistry)
T-lymphocytes
—cell mediated immunity—kill foreign and virus infected cells, regulate other WBC
proliferate then differentiate—cytotoxic (cell killer), helper and suppressor (regulate other WBC)
B-lymphocytes
—humoral immunity—production of antibody
proliferate then differentiate into plasma cells which synthesize and secrete antibody
Monocytes
—4-8% of WBC, 12-25um
nucleus kidney or horseshoe shaped, chromatin is less dense than other mature leukocytes
cytoplasm is extensive and contains azure granules (lysosomes), vacuoles and residual bodies
highly motile—after 1-2 days in blood, they migrate into tissue and differentiate into macrophages
unlike neutrophils, they may undergo further division and enzyme synthesis, survive for months
mononuclear phagocytic system
—monocytes + macrophages dispersed throughout the body
phagocytosis and digestion of foreign organisms and senescent cells, also present antigen to lymphocytes
Slides
blood/bone marrow smear—drop of blood spread into thin film on a glass slide, air dred/MeOH fixed
stained with a mixture of dyes originally developed by Romanovsky
Wright's stain—modified Romanovsky—methylene blue (basic), azure n (basic), and eosin (acidic)
Blood Smear
—human peripheral blood—can identify RBC, platelets, small and medium lymphocytes, monocytes, neutrophils, eosinophils, and basophils (rare, less than 1% in peripheral blood)
The nuclei of the leukocytes are stained with azure component (purple-pink)
lymphocytes - round, oval, with dense chromatin, occupying most part of the cell
monocytes - kidney-shaped chromatin pale to moderately dense
neutrophils - 2 - 5 lobes, chromatin coarse and clumpy
basophils - 2 lobes or S-shaped, chromatin coarse, usually obscured by dark cytoplasmic granules
eosinophils - 2 lobes, coarse chromatin
Cytoplasm is usually not stained except in:
erythrocyte - orange-red (eosinophilic)
monocyte - slight gray-blue
lymphocyte - light blue
Many blood cell types azurophilic granules (red-purple) in cytoplasm:
neutrophils
platelets
some lymphocytes and monocytes
Granulocytes contain specific granules
neutrophils - not easily resolved at light microscopic level, give salmon-pink color to the cytoplasm
eosinophils - orange-red large refractile granules
Granulopoiesis (identify stages promyelocyte to mature form for neutrophils)
Myeloblast
Promyelocyte
Myelocyte
Metamyelocyte
band form
mature granulocyte (segmented granulocyte)
Non-granular leukocyte developmental stages
Monocyte precursors: monoblasts and promonocytes
Lymphocyte precursors: lymphoblasts and prelymphocytes—difficult to distinguish
small lymphocyte
plasma cell - antigen stimulated B - lymphocyte, large amount of basophilic cytoplasm - with eccentric, dense, clock-faced nucleus. Compare with basophilic normoblast and polychromatic normoblast and myelocyte.
Megakaryocyte - the largest cell with the largest nucleus - azure granules in cytoplasm