What are Basophils ?





Basophils are a rare type of granulocytes that play a role in keeping the immune system functioning correctly. Also they have a integral role in preventing blood clotting due to heparin released by this cells.

Normal range

Basophils normal range, is about 0.01- 0.1X109/L of blood. 

As a percentage it is less than 1% of total WBCs.


Basophils have bi-lobed nucleus which tend to fold up on each other. And also they have numerous dark blue/purple granules which are vary in size.

These granules contain histamine, heparin and serotonin. As there are so many granules it is difficult for us to see the cytoplasm.


Why and When High Basophil counts ?

Increased number of basophils in blood is called as basophilia. Myeloproliferative neoplasms and chronic myelogenous leukemia can give high basophil counts. Also high Basophil counts may be a sign of low thyroid gland function.

Basophils have receptors for immunoglobulin, IgE (an antibody) concerned with allergic reactions

 When an antigen combines with the antibody, cell releases heparin, histamine from granules. These substances cause inflammatory and allergic reactions. Basophils are involved together with mast cells in tissues in these reactions.

Why and When High Basophil counts ?

As Basophil account for <1% of total WBCs  , it is very rare to see Basophils in blood smear of healthy subjects. If the basophil counts are less than normal it is called as Basophenia. There is no clinically much importance on it. However, It can be caused by infections, severe allergies,or due to overactive thyroid gland.

Tests available

Most of the time clinician’s may request to do Full blood count if they are looking for person’s basophil levels. Differential White blood cell count is necessary to find the absolute basophil count. 

Basophil activation test Is a specific test that to check for particular allergens, especially for patients having allergies.

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