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− | {{review}}
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− | <p>Leukopoiesis is the process of formation of [[Leukocytes|leukocytes]] (white blood cells) from stem cells in haematopoietic organs. Leukocytes develop from either multipotential myeloid stem cells ([[Haematopoiesis#Colony Forming Units|CFU-GEMM]]) or multipotential lymphoid stem cells ([[Haematopoiesis#Colony Forming Units|CFU-L]]). </p>
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− | <p>[[Leukocytes|Leukocytes]] developing from CFU-GEMM’s are granulocytes ([[Neutrophils|neutrophils]], [[Basophils| basophils]] and [[Eosinophils| eosinophils]]) or [[Monocytes|monocytes]] and [[Leukocytes|leukocytes]] developing from [[Haematopoiesis#Colony Forming Units|CFU-L]]'s are lymphocytes (T & B cells, dendritic and NK cells).</p>
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| [[Image:Leukopoiesis pathway.jpg|right|thumb|400px|'''Leukopoiesis pathway''']] | | [[Image:Leukopoiesis pathway.jpg|right|thumb|400px|'''Leukopoiesis pathway''']] |
| + | ==Introduction== |
| + | <p>Leukopoiesis is the process of formation of [[Leukocytes|leukocytes]] (white blood cells) from stem cells in haematopoietic organs. Leukocytes develop from either multipotential myeloid stem cells ([[Haematopoiesis - Overview#Colony Forming Units|CFU-GEMM]]) or multipotential lymphoid stem cells ([[Haematopoiesis - Overview#Colony Forming Units|CFU-L]]). </p> |
| + | <p>Leukocytes developing from CFU-GEMM’s are granulocytes ([[Neutrophils|neutrophils]], [[Basophils| basophils]] and [[Eosinophils| eosinophils]]) or [[Monocytes|monocytes]]. |
| + | Leukocytes developing from CFU-Ls are [[:Category:Lymphocytes|lymphocytes]] (T & B cells, dendritic and NK cells).</p> |
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| ==Granulopoiesis== | | ==Granulopoiesis== |
− | All granulocytes develop from the [[Haematopoiesis#Colony Forming Units|CFU-GEMM]] cells. | + | All granulocytes develop from the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GEMM]] cells. |
| + | |
| ===Summary of pathways=== | | ===Summary of pathways=== |
− | <div style="text-align: center;">
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| {| cellpadding="10" cellspacing="0" border="1" align="left" | | {| cellpadding="10" cellspacing="0" border="1" align="left" |
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| !Basophil | | !Basophil |
| !Eosinophil | | !Eosinophil |
− | |rowspan="10"|<p>[[Image:LH_Developing_granulocytes_Histology.jpg|200px|Developing granulocytes]]</p><sup>©RVC 2008</sup> | + | | rowspan="10" |<p>[[Image:LH_Developing_granulocytes_Histology.jpg|200px|Developing granulocytes]]</p><sup>©RVC 2008</sup> |
| |- | | |- |
| !Stem cell | | !Stem cell |
− | |colspan="4"|CFU-GEMM | + | | colspan="4" |CFU-GEMM |
| |- | | |- |
| !CFU | | !CFU |
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| |CFU-Eo | | |CFU-Eo |
| |- | | |- |
− | !Factors | + | !Cytokines |
− | |<p>GM-CSF</p><p>Il-3</p><p>M-CSF</p> | + | |<p>GM-CSF</p><p>IL-3</p><p>M-CSF</p> |
− | |<p>GM-CSF</p><p>Il-3</p><p>G-CSF</p> | + | |<p>GM-CSF</p><p>IL-3</p><p>G-CSF</p> |
− | |valign="top"|<p>GM-CSF</p><p>Il-3</p> | + | | valign="top" |<p>GM-CSF</p><p>IL-3</p> |
− | |<p>GM-CSF</p><p>Il-3</p><p>Il-5</p> | + | |<p>GM-CSF</p><p>IL-3</p><p>IL-5</p> |
| |- | | |- |
− | !Rowspan="6"|Stages | + | ! rowspan="6" |Stages |
| |Monoblast | | |Monoblast |
− | |colspan="3"|Myelocyte | + | | colspan="3" |Myelocyte |
| |- | | |- |
| |Promonocyte | | |Promonocyte |
− | |colspan="3"|Promyelocyte | + | | colspan="3" |Promyelocyte |
| |- | | |- |
− | |rowspan="4"|Monocyte | + | | rowspan="4" |Monocyte |
| |Neutrophilic Myelocyte | | |Neutrophilic Myelocyte |
| |Basophilic Myelocyte | | |Basophilic Myelocyte |
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| |- | | |- |
| |Neutrophilic Metamyelocyte | | |Neutrophilic Metamyelocyte |
− | |rowspan="2"|Basophilic Metamyelocyte | + | | rowspan="2" |Basophilic Metamyelocyte |
− | |rowspan="2"|Eosinophilic Metamyelocyte | + | | rowspan="2" |Eosinophilic Metamyelocyte |
| |- | | |- |
| |Band Cell | | |Band Cell |
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| |Eosinophil | | |Eosinophil |
| |} | | |} |
− | </div>
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| <Br clear="left"> | | <Br clear="left"> |
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− | ===[[Neutrophils|Neutrophils]]=== | + | ==Neutrophils== |
− | Under the stimulation of GM-CSF, G-CSF and Il-3 the [[Haematopoiesis#Colony Forming Units|CFU-GEMM]] differentiates into the [[Haematopoiesis#Colony Forming Units|CFU-GM]], the common precursor for both neutrophils and monocytes. This then further differentiates into the [[Haematopoiesis#Colony Forming Units|CFU-G]]. | + | Under the stimulation of [[Cytokines|cytokines]] GM-CSF, G-CSF and IL-3 the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GEMM]] differentiates into the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GM]], the common precursor for both neutrophils and monocytes. This then further differentiates into [[Haematopoiesis - Overview#Colony Forming Units|CFU-G]]. |
− | ====Stages====
| + | ===Stages:=== |
− | =====Myeloblast=====
| + | ====Myeloblast==== |
− | Large cell with a large nucleus and stains basophilic. Same stage exists for all granulocytes. | + | Large cell with a large nucleus and which demonstrates basophilic staining. This stage exists for all granulocytes. |
− | =====Promyelocyte=====
| + | |
− | During this stage primary (azurophilic) granules are formed. Same stage exists for all granulocytes. | + | ====Promyelocyte==== |
− | =====Neutrophilic myelocyte=====
| + | During this stage primary (azurophilic) granules are formed. This stage exists for all granulocytes. |
− | Developing neutrophil can now be differentiated from basophils and eosinophils as specific granules are now being formed.
| + | |
− | =====Neutrophilic metamyelocyte=====
| + | ====Neutrophilic myelocyte==== |
− | At this stage mitosis can no longer occur. The nucleus elongates, becomes heterochromatic and has a kidney like shape. Differentiation is now much clearer between other granulocytes as the specific granules are in a far greater number than the primary granules formed in the promyelocyte stage. | + | The developing neutrophil can now be differentiated from basophils and eosinophils as neutrophil specific granules are now being formed. |
| + | |
| + | ====Neutrophilic metamyelocyte==== |
| + | At this stage mitosis can no longer occur. The nucleus elongates, becomes heterochromatic and has a kidney like shape. Differentiation is now much clearer from other granulocytes as the specific granules are in a far greater number than the primary granules formed in the promyelocyte stage. |
| | | |
− | =====Band cell=====
| + | ====Band cell==== |
| Nucleus elongates further and represents a horse shoe. Nucleus starts to segment. | | Nucleus elongates further and represents a horse shoe. Nucleus starts to segment. |
− | =====Neutrophil=====
| + | ====Neutrophil==== |
| Mature neutrophil is formed and the nucleus is segmented and has 3 to 5 lobes. This lobular structure of the nucleus gives rise to the name polymorphonuclear neutrophil. | | Mature neutrophil is formed and the nucleus is segmented and has 3 to 5 lobes. This lobular structure of the nucleus gives rise to the name polymorphonuclear neutrophil. |
| <br> | | <br> |
− | ===[[Basophils|Basophils]]=== | + | |
− | Under the stimulation of GM-CSF and Il-3 the [[Haematopoiesis#Colony Forming Units|CFU-GEMM]] differentiates into the [[Haematopoiesis#Colony Forming Units|CFU-Ba]]. | + | ==Basophils== |
− | ====Stages====
| + | Under the stimulation of GM-CSF and IL-3, the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GEMM]] differentiates into [[Haematopoiesis - Overview#Colony Forming Units|CFU-Ba]]. |
− | ===== Myeloblast & Promyelocyte=====
| + | ===Stages:=== |
− | These stages are common to all granulocytes and no distinction can be made between different cell lines. See [[#Stages|neutrophil stages]] for further information. | + | ====Myeloblast & Promyelocyte==== |
− | =====Basophilic myelocyte & metamyelocyte=====
| + | These stages are common to all granulocytes and no distinction can be made between different cell lines. |
− | Specific granules start to appear in the myelocyte stage and once the cell has reached the metamyelocyte stage it cannot undergo further mitosis. | + | |
− | =====Basophil=====
| + | ====Basophilic myelocyte & metamyelocyte==== |
− | Final nuclear shape is masked by high density of granules. | + | Specific granules start to appear in the myelocyte stage, and as the cell develops into the metamyelocyte stage, mitosis ceases. |
| + | |
| + | ====Basophil==== |
| + | Final nuclear shape is masked by the high density of cytoplasmic granules. |
| <br> | | <br> |
| | | |
− | ===[[Eosinophils|Eosinophils]]=== | + | ==Eosinophils== |
− | Under the stimulation of GM-CSF, Il-3 and Il-5 the [[Haematopoiesis#Colony Forming Units|CFU-GEMM]] differentiates into the [[Haematopoiesis#Colony Forming Units|CFU-Eo]]. | + | Under the stimulation of GM-CSF, IL-3 and IL-5 the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GEMM]] differentiates into the [[Haematopoiesis - Overview#Colony Forming Units|CFU-Eo]]. |
− | ====Stages====
| + | ===Stages:=== |
− | ===== Myeloblast & Promyelocyte=====
| + | ====Myeloblast & Promyelocyte==== |
− | These stages are common to all granulocytes and no distinction can be made between different cell lines. See [[#Stages|neutrophil stages]] for further information. | + | These stages are common to all granulocytes and no distinction can be made between different cell lines. |
− | =====Eosinophilic myelocyte & metamyelocyte=====
| + | |
| + | ====Eosinophilic myelocyte & metamyelocyte==== |
| Specific granules start to appear in the myelocyte stage and once the cell has reached the metamyelocyte stage it cannot undergo further mitosis. | | Specific granules start to appear in the myelocyte stage and once the cell has reached the metamyelocyte stage it cannot undergo further mitosis. |
− | =====Eosinophil=====
| + | ====Eosinophil==== |
− | Mature cell has a bilobed nucleus. | + | Mature cell has a bilobed nucleus. There are species specific variations in granule size once stained. |
| <br> | | <br> |
| | | |
− | ==Monocyte development== | + | ==Monocytes== |
− | [[Monocytes|Monocytes]] develop from the same precursor as [[Neutrophils|neutrophils]] the [[Haematopoiesis#Colony Forming Units|CFU-GM]]. This then differentiates into the [[Haematopoiesis#Colony Forming Units|CFU-M]] under the influence of GM-CSF, IL-3 and M-CSF.
| + | Monocytes develop from the same precursor as neutrophils - the [[Haematopoiesis - Overview#Colony Forming Units|CFU-GM]]. This then differentiates into the [[Haematopoiesis - Overview#Colony Forming Units|CFU-M]] under the influence of GM-CSF, IL-3 and M-CSF. |
− | ===Stages=== | + | ===Stages:=== |
| ====Monoblast==== | | ====Monoblast==== |
− | First stage after cell has differentiated into the [[Haematopoiesis#Colony Forming Units|CFU-M]].
| + | This is the first stage after cell has differentiated into the [[Haematopoiesis - Overview#Colony Forming Units|CFU-M]]. |
| ====Promonocyte==== | | ====Promonocyte==== |
− | Cell has a large nucleus and basophilic cytoplasm and consists of two populations:- One rapidly dividing and the other slowly dividing (acting as a reservoir). | + | Cell has a large nucleus and basophilic cytoplasm and consists of two populations:- One rapidly dividing and the other slowly dividing, which acts as a reservoir. |
| + | ====Monocyte==== |
| + | Monocytes are incapable of mitosis and enter the circulation. They have a large kidney shaped nucleus with a slightly basophilic cytoplasm, which is often vacuolated. |
| | | |
− | ====[[Monocytes|Monocyte]]==== | + | ====Macrophage==== |
− | Monocytes are incapable of mitosis and enter circulation. They have a large kidney shaped nucleus with a slightly basophilic cytoplasm.
| + | Once the monocyte has entered tissue it differentiates into a macrophage. |
− | ====[[Macrophages|Macrophage]]====
| |
− | Once the monocyte has entered tissue it differentiates into a [[Macrophages|macrophage]]. | |
| | | |
| ===Dendritic cells=== | | ===Dendritic cells=== |
− | Develop from the monoblast under the stimualtion of GM-CSF and IL-4 into an immature dendritic cell. This then develops into the mature dendritic cell under stimulation of TNF-α.
| + | These develop from the monoblast under the stimualtion of GM-CSF and IL-4 into an immature dendritic cell. This then develops into the mature [[T_cell_differentiation#Dendritic_Cells|dendritic cell]] under stimulation of TNF-α. |
| <br> | | <br> |
| | | |
| ==Lymphopoiesis== | | ==Lymphopoiesis== |
− | <p>[[Lymphocytes|Lymphocytes]] develop from the [[Haematopoiesis#Colony Forming Units|CFU-L]]'s. Those destined to become [[Lymphocytes#T cells|T cells]] leave the [[Bone Marrow - Anatomy & Physiology|bone marrow]] and migrate to the [[Thymus - Anatomy & Physiology|thymus]], and those destined to be [[Lymphocytes#B cells|B cells]] migrate to the [[Spleen - Anatomy & Physiology|spleen]] and GALT or proliferate directly from the [[Bone Marrow - Anatomy & Physiology|bone marrow]].</p><p>Follow these links for a more detailed explanation on [[T cell differentiation - WikiBlood|T cell development]] and [[B cell differentiation - WikiBlood |B cell development]].</p>
| + | [[Lymphocytes - Introduction|Lymphocytes]] develop from the [[Haematopoiesis - Overview#Colony Forming Units|CFU-L]]'s. Those destined to become [[T cells]] leave the [[Bone Marrow - Anatomy & Physiology|bone marrow]] and migrate to the [[Thymus - Anatomy & Physiology|thymus]], and those destined to be [[B cells]] migrate to the [[Spleen - Anatomy & Physiology|spleen]] and gut-associated lymphoid tissue (GALT) or proliferate directly from the bone marrow. |
| {|cellpadding="5" cellspacing="1" border="1" | | {|cellpadding="5" cellspacing="1" border="1" |
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| |colspan="4"|CFU-L | | |colspan="4"|CFU-L |
| |-align="center" | | |-align="center" |
− | |style="background-color:#ffffcc"|<sup>▼Il-7 & Il-11</sup> | + | |style="background-color:#ffffcc"|<sup>▼IL-7 & IL-11</sup> |
− | |colspan="3" style="background-color:#e6e6fa"|<sup>▼Il-7 & SCF</sup> | + | |colspan="3" style="background-color:#e6e6fa"|<sup>▼IL-7 & SCF</sup> |
| |-align="center" | | |-align="center" |
| |style="background-color:#ffffcc"|B lymphoid cell progenitor | | |style="background-color:#ffffcc"|B lymphoid cell progenitor |
| |colspan="3" style="background-color:#e6e6fa"|T lymphoid cell progenitor | | |colspan="3" style="background-color:#e6e6fa"|T lymphoid cell progenitor |
| |-align="center" | | |-align="center" |
− | |style="background-color:#ffffcc"|<sup>▼Il-3 & Il-7</sup> | + | |style="background-color:#ffffcc"|<sup>▼IL-3 & IL-7</sup> |
− | |style="background-color:#e6e6fa"|<sup>▼Il-7</sup> | + | |style="background-color:#e6e6fa"|<sup>▼IL-7</sup> |
− | |style="background-color:#e6e6fa"|<sup>▼Il-2, IL-12 & Il-18</sup> | + | |style="background-color:#e6e6fa"|<sup>▼IL-2, IL-12 & IL-18</sup> |
− | |style="background-color:#e6e6fa"|<sup>▼Il-3, Il-6, GM-CSF & SCF</sup> | + | |style="background-color:#e6e6fa"|<sup>▼IL-3, IL-6, GM-CSF & SCF</sup> |
| |-align="center" | | |-align="center" |
| |style="background-color:#ffffcc"|Pre-B cell | | |style="background-color:#ffffcc"|Pre-B cell |
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| |} | | |} |
| <p>'''Note:''' | | <p>'''Note:''' |
− | *That between the 'pre-[type] cell' stage and the final mature all the lymphocytes are referred to as 'immature [type] cells'. | + | *Between the 'pre-[type] cell' stage and the final mature all the lymphocytes are referred to as 'immature [type] cells'. |
− | * T cell differentiation into it's different forms (helper, cytotoxic and T cell with regulator functions) is under stimulation by Il-10 & TNF-γ</p> | + | * T cell differentiation into helper, cytotoxic and T cells with regulator functions is induced by IL-10 & TNF-γ |
| [[Category:Haematopoiesis]] | | [[Category:Haematopoiesis]] |