White Blood Cell Functions & Normal Count Range

Presentation Notes on LEUKOCYTES (WBC) definition, Roles in Blood, Low High Counts & Classifications for Students & Kids in word/ .doc Format

THE LEUKOCYTES

Leukocytes are also called white blood corpuscles, WBC fundamental job of the WBCs is to provide defense against

  • Bacteria
  • Fungus
  • parasite
  • Virus and
  • cancer
They also remove debris (e.g dead cells in our body) and foreign protein. For this, these WBCs 

  • Either directly attack the bacteria
  • Produce antibodies which attack the antigen.

The WBCs also produce chemicals which produce inflammation         

CLASSIFICATION

1. Granulocytes  -  with granules (Neutrophils,Eosinophils and Basophils)
2. Agranulocytes – without granules (Monocytes and Lymphocytes).

FACTORS HELPING THE PROLIFERATION OF LEUKOCYTES IN THE RBM. THE GROWTH FACTORS

For WBC proliferation, growth factors are required. These growth factors are many in number. The chief of them are:

  1. Erythropoietin
  2. Interleukins
  3. SCF
  4. GM-CSF
  5. CSF-I or M-CSF
  6. Thrombopoietin.

Note, hematopoetic growth factor is a term which includes erythropoietin, thrombopoietin, as well as myeloid growth factors. By myeloid growth factors, one usually means factors helping the proliferation of neutrophil eosinophil-basophil-monocyte precursors.

Erythropoietin, is required fundamentally for RBC proliferation. Thrombopoie­tin has been described in connection with platelet develop­ment. Other growth factors have been briefly described below:

Interleukins. (1) Lymphocytes, (2) macrophages, (3) endothe­lial cells and many other cells produce chemicals which behave like hormones, ie, after being released they act on their target cell (note, the target cell is a different cell from the cell which produces the hormone like substance). All such chemicals are called, "cytokines" [= substances which produce kinesia or movements, that is chemical changes, on the (target) cells]. All such cytokines are proteins in nature; where the amino acid sequence of the cytokine is known, the cytokine is called, "interleukin" [Lymphokines are cytokines produced by the lymphocytes.] Till to date, 13 interleukins (lLs) have been identified and named IL-l, IL-2 through IL-13. Of all the ILs, the IL-1 is best known, best studied.


ILs have very wide spread activities. Different ILs have different effects, although many actions overlap. Many ILs are, however, principally involved in immune mechanism as well as neutrophil mediated inflamma­tion. But many of them have other effects. Probably many of the ILs, act as myeloid growth factors, stimulating the proliferation of the stem cells, but most well known in this respect, are IL-l, IL-6 and IL-3. IL-l, IL-6 and IL-3 act on the pluripotent stem cell, thus, helping the development of committed stem cells.

GM-CSF (granulocyte-monocyte colony stimulating factor. This myeloid growth factor stimulates primarily the proliferation of committed stem cell precursors of the granulocyte-monocyte-megakaryocyte.

M-CSF→ It helps primarily the proliferation of the precur­sors of monocyte.

SCF→ Stimulates the pleuripotent and committed stem cells. Also helps to increase the number of B lymphocytes.

Some of the growth factors are avail­able commercially and used therapeutically, particularly in such cases like bone marrow transplantation.    
                           
STAINING A blood film is stained by one of the variants of Romanowski’s .the well known variants of the Romanowski’s stains include:

  1. Leishman’s
  2. Wright’s
  3. Geimsa          
  4. Jenner’s and so on.
The total count, TC of the WBC is 5,000 – 10000 ∕cu.mm

Concept of pool

The WBCs reside in :-

  • Marrow pool,
  • blood pool and
  • tissue pool.
for example in case of Neutrophills 90% of them stay in marrow pool, 3% in the blood pool and 7% in the tissue pool. Blood pool is again divided into two subclasses-circulating pool and marginal pool. In case of Eosinophills most of them reside in the tissue pool.

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