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ICS-Heme-Hematopoiesis & BM Failure


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2.mast cell precursor
3.vasoactive amines
NK cells?
viral imm (b/c kill the whole cell, and viruses usually intracellular)
process of hematopoiesis req:
1.stem cell pool
2.hematopoetic cytokines
3.stroma (supportive environ)
PHSC's (pluripotent hematopoietic stem cells) express what antigen?
ONLY CD34 (this is lost as cells differentiate)
what properties do PHSC's have?
1.self renewal
-what are the earliest sites of PHSC prolif and differentiation?
-when and where do they appear?
blood islands
-appear at 6 wks in the yolk sac
what happens after blood islands? during what time period
-cells migrate from yolk sac to liver and spleen, where organ hemotopoiesis occurs thru 15th wk gestation
desc embryology of hematopoiesis
A. 6 wks: blood islands (earliest site of PHSC prolif and differentiation) appear in yolk sac.
B. 6 wks-15 wks: PSCSs in liver and spleen (organ hematopoiesis)
C. 15 wks: BM (primary site of blood cell production thru remainder of gestation and post-birth life)
what dio PHSC's arise from?
mesenchymal tissue
extramedullary hematopoiesis
=heamtopoiesis outside the BM
-in times of stress (i.e. CML), liver and spleen become HUGE b/c they revert to blood-forming organs
what drives differentiation of PHSC's?
hematopoietic cytokines (hormones that regulate blodo cell production)
AND many cytokines are promiscuous (act on >1 lineage at >1 level of hematopoiietic development, i.e. IL3)
what is leukoerythroblastic rxn?
what does this suggest?
presence of immature WBC's and nucleated RBC's
-suggests infiltrative process in BM
tear-drop RBC's
suggests infiltrative process in BM (metastatic tumor, fibrosis, granuloma)
hypercellular BM and peripheral cytopenia
myelodysplastic syndrome (a "premalignant" condition)
first sign of BM failure

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