Elekanglkrvetvorba
1. Hemopoiesis as a self-renewal system. Stem cell of hemopoiesis
2. Unipotent (determined) progenitors, proliferation-differentiation and maturation compartments. Methods of their study
3. Regulation of the hemopoietic system
4. Systems analysis of the hemopoietic function in physiological and pathophysiological conditions
5. Structure and physiology of RBC
-
Hemopoiesis as a self-renewal system. Stem cell of hemopoiesis
A self-renewal system loses mature (functional) cells steadily and replaces them continually. Normally it is composed of three cellular compartements:
-
pluripotent stem cells which are capable of
-
non declining (steady) autoreproduction
-
differentiating into various developmental lines (pluripotentiality)
-
unipotent cells capable of dividing (proliferation)
-
differentiated functional (postmitotic) cells unable of division
Blood forming organs represent a typical example of a self-renewal system (Fig. 1n = Haen 3.8). All non-stem populations are transitory. The transit times in the individual compartements – tab. 1 = Haen tab. 3.1.
Two types of damage:
-
loss of mature cells (e.g., bleeding, inflammation)
-
damage to the stem cell and precursor compartement (e.g., radiation, cytotoxic drugs)
Lymphatic organs are totally dependent on the marrow
Fig 2 = Haen 4.1: Erythropoiesis, the development and maturation of the red blood cells
-
Unipotent (determined) progenitors, proliferation-differentiation and maturation compartments. Methods of their study
The historically first method of the stem cell detection: colony forming units spleen (CFU-S)
Fig 3 = stará blána fig. 2 A,B,C, Fig. 4 = fig. 3 stará blána: The stages which cannot be differentiated morphologically are detected by means of short-term colonies in vitro
Besides, the stem and precursor cells could be identified by means of flow cytometry ( numbers of different cells) and light-activated cell sorting ( preparing of homogenous cell populations) (Fig. 5 = fig. 4 stará blána)
-
Regulation of the hemopoietic system
Fig. 6= fig, 6 stará blána: Hemopoietic inductive microenvironment (HIM)
-
fibroblast-type „reticulum“ cell – granulopoietic islands
-
macrophage-type „reticulum“ cell – erythroblastic islands
Cytokines = peptides taking part in the signalling among the immune and hematopoietic system cells. No hormones (endocrine). Types:
- Interleukins (Il-1, 2,...etc.)
MF, T cells, stromal cells (HIM) growth and differentiation of
- lymphocytes
-
hematopoetic stem cells (some of them are known as „colony stimulating factors“, CSF)
Interleukins taking part in steady-state hemopoiesis:
-
multi-CSF (= Il-3) from helper T-cells
-
GM-CSF
-
Il-6
-
Il-7 (development of B- and T-lymphocytes)
In non-steady-state-conditions: production of a number of growth factors more specific in their actions which are usually produced by activated blood cells or fibroblasts: Il-4 and Il-9 (production of basophils and mast cells), Il-5 (eosinophils), G-CSF, M-CSF, EPO
-
Interferons: induced in response to a variety of agents including viruses, microorganisms and endotoxins. Upon induction, they circulate to neighboring cells which they stimulate to make antiviral proteins
-
Lymphokines: Proteins secreted by some helper T cells after they are primed by contact with an antigen. Are not antibodies but are mediators of cellular immunity. They activate various white blood cells, incl. other lymphocytes. Examples: interleukin 2, some interferons, migration inhibition factor (MIF)
-
Tumor necrosis factors: have cytotoxic effects on tumor cells but not on normal cells. TNF is secreted by macrophages in response to bacterial infection and other challenges, TNF by helper T lymphocytes and cytotoxic lymphocytes. Synergistic with interferons
-
Systems analysis of the hemopoietic function in physiological and pathophysiological conditions
The homeostasing of the blood cell production is regulated by several feedbacks. Their interplay may be rather complex and can be understood by means of mathematical modelling only (Fig. 7, 8, 9 = fig. 1, 7 a 8 z Wichmanna)
-
Structure and physiology of RBC
The RBS have lost
- mitochondria, citric acid cycle and oxydative phosphorylation forming ATP anaerobic glycolysis must be the main source of ATP in them;
- ribosomes no protein synthesis, detrition of enzymes etc.
RBC membrane:
Fig. 10 = blána fig. 10: glycophorins can attach lectins = phytohemagglutinins, viruses and malaria parasites
Fig. 11 = blána fig. 11: Spectrin and aktin filamentous network responsible for the biconcave shape of RBC; ankyrin links spectrin molecules to anion-transport proteins („band 3“)
Hemoglobin protection against oxidation (Fig. 12)
RBC shape and its life span (Fig. 13 = blána 12B)
Elekanglanemie Anemias 1. In general
2. Decreased erythrocyte production
3. Increased erythrocyte loss
-
In general
Definition
- traditional RBC or Hb or HTC
- alternative Erythron (M)
M = I * T,
where I = amount of new RBC produced per unit of time
T = red blood cell life span
Example (extreme compensation): M = 8 * 1/8 = 100%
Symptoms: under 80g Hb/L
Hemolysis jaundice, splenomegaly, cholelithiasis
O2 diffusion vasoconstriction of skin and kidneys
Pulmonary and cardiac function
Medullary erythropoiesis
2,3 diphosphoglycerate shift of the Hb curve to the right O2 delivery to the tissues
Acute blood loss:
30% of volume (1500 mL) circulatory colaps, shock
50% loss death
Hb after 2-3 days
No „emergency“ pool of RBC, premature release of reticulocytes only
The marrow RBC production can rise up to 8times, if there is Fe enough
Classification of anemias (Fig. 14 = Haen tab. 8.2)
2 Decreased erythrocyte production
21 Decreased proliferation of new erythrocytes = aplastic anemia s.l. = hypoproliferative anemia (Fig. 15 = Haen 9.1)
Reticulocyte index . Hypoplasia of the red cell line in the marrow inability to react to anemia
Name: in fact, the anemia is hypoplastic only (never complete aplasia)
Symptomatology: pancytopenia always present (white cells, platelets), infections, bleeding, reticulocytes, plasma Fe, total binding capacity
Prognosis not very good. Ther.: bone marrow transplantations and immunosuppression (cyclosporine and antilymphocyte serum)
Etiology
-
„idiopathic“ – most often, probably caused by so far unknown pollutants
-
known causes
-
primary (= inborn) – Fanconi´ s anemia
-
secondary (= acquiered):
211 Decreased erythropoietin
Impaired production by the kidneys - anemia of renal failure
Low oxygen requirements - anemia of endocrine disease (hypothyreoidism)
Impaired stem cell response to erythropoietin - anemia of chronic diseases (see later)
212 Bone marrow damage or defect
Replacement of marrow by tumor (crowding out) - myelophthisic anemia
Replacement of normal marrow by cancerous cell line - anemia associated with myeloproliferative disease
Local competition for nutrients, secretion of inhibitory substances
Damage to bone marrow by physical or chemical agents, or infections – aplastic anemia s.s.
Benzene, chloramphenicol, analgesics, anticonvulsants, antianxiety drugs
Inherited bone marrow defect - Fanconi's anemia
Multiple congenital abnormalities, recessive gene
22 Impairment in the maturation of new erythrocytes ineffective erythropoiesis
Subcellular pathology defective erythroblasts intramedullary hemolysis (50%). The marrow is hypercellular, in spite of this, the reticulocytes are scanty ineffective erythropoiesis
221 Macrocytic-normochromic erythrocytes
macrocytic
alcohol
liver dis.
myxedema
gravidity megaloblastic
myeloma
enzymatic disturb.
anomalous vitamins
folic acid and B12
Derangement of DNA synthesis
Slowering of cellular proliferation
Nucleo-cytoplasmic asynchrony („dissociation“)
Normal Hb production
Fe
PITR (plasma iron
transit rate)
RBC volume (MCV), ovalocytosis
normal Hb concentration inside (MCHC)
T
RBC, HTC, anisocytosis and poikilocytosis always present, leucocytes and platelets, hypersegmented neutrophils
Atrophic glossitis, purpura
Folic acid deficiency (Megaloblastic anemia, Fig. 16 = Haen 10.1)
Folate compounds widely distributed in nature, rich in the diet, but small body stores. Fig. 17 = tab. Haen 10.1. Decreased intake: alcoholism, hepatic diseases, tropical sprue (coliform bacteria), malabsorption, resections. Increased requirements: gravidity, growth, hematopoiesis. Folic acid antagonists: cytostatics, chemotherapeutics, antiparasitic and anticonvulsive drugs
Function of tetrahydrofolate: coenzyme for single-carbon transfers necessary for thymidylate synthase rate limiting for DNA synthesis
Vitamin Bl2 deficiency (Megaloblastic anemia)
Synthetized by microbes only in foods of animal origin. Requirements small, stores large. Absorption of B12 Fig. 18 = Haen 10.8
Function of B12: myelin (funicular myelosis) and folate synthesis
Deficiency:
- total vegetarianism
- malabsorption syndromes (jejunal bacterial overgrowth, enteritis, intestinal parasites)
- lack of intrinsic factor pernicious anemia
adults: genetic, autoantibodies against parietal cells or IF
chronic atrophic gastritis
children: rare, inherited, abnormalities of IF
222 Microcytic-hypochromic erythrocytes
Iron deficiency (Iron deficiency anemia)
Fe absorption
in animal food – in hem
Fe2+ easily absorbable
in plant food – inorganic
Fe3+ presupposes low pH in the stomach for solubilization
Absorption is regulated by the needs (i.e., by hematopoiesis) – by the Fe content in the mucosal gut cells
Etiology of Fe deficiency: blood losses, need, malabsorption
Iron metabolism (Fig. 19 – Kaufm.)
Incorporation of Fe into the erythroblasts only from transferrin
Ferritin: a protein envelope surrounds a microcrystalic core of inorg. Fe
Fe overload: disturbance of the gut mucosal cells. Hemosiderosis = RES cell containing hemosiderin, hemochromatosis = various organs contain hemosiderin
Clinics: angular stomatitis, glossitis, koilonychia, dysphagia, pica, no sideroblasts, typical serum composition (Fig. 20 – Kaufm.)
Development of microcytic anemia (Fig. 21 – Kaufm.)
Other microcytic-hypochromic anemias
Abnormalities of the heme or globin synthesis Hb production more than 4 divisions microcytosis and hypochromia
Unavailability of iron to blast cells - Anemia of chronic disease (ACD)
Block of Fe metabolism: macrophages degrading Hb of the decayed RBC are activated, proliferate and retain Fe for themselves
hepatic syntheses transferrin together with plasma Fe (Fig. 22 = fig. 14 na blánách)
Fe storage normal or
Besides
- EPO production or its binding to the stem cells (loss of EPO receptors, disturbed coupling)
- RBC life span
Etiopathogenesis: foreign antigenes pertaining to the inflammatory process activation of macrophages
Il-1 and TNF production: Fe metabolism in MF disturbed; direct inhibition of EPO production
Conditions: chronic inflammations (e.g. hepatitis), some malignancies, collagen-vascular diseases
Impairment of heme synthesis (Sideroblastic = sideroachrestic anemia)
Fe into mitochondrias ring erythroblasts
Etiology:
-
inherited – aminolevulate synthetase – rate limiting
-
acquiered – somatic mutation – cell clone
Impairment of globin synthesis (Thalassemia syndromes)
Fig . 23 (má blána)
3 Increased erythrocyte loss
31 Hemorrhage hemorrhagic anemia
Acute: influx of interstitial fluid into the circulation (several days) progressive fall of Hb, HTC, RBC
EPO and reticulocyte response (Fig. 25 and 26 = Haen 13.1 a 13.2)
Chronic: GI ulcers and malignancies, menstruation. Iron stores
32 Intravascular hemolysis or premature phagocytosis hemolytic anemia
321 Hereditary factors
Defects in the erythrocyte membrane
Hereditary spherocytosis
RBC flexibility is conditioned by the unique structure of the RBC membrane, and this is maintained by actin, spectrin, and ankyrin. Spectrin gene mutates most often
a) Mutated RBC loss of flexibility pitting in the splenic sinuses RBC shrinking getting spherical loss of flexibility destruction in the spleen
b) Mutated RBC slowering of the Na/K-ATPase Na into RBC water into RBC getting spherical etc.
c) Mutated RBC enhanced need of glucose lowered glucose concentration in the spleen enhanced trapping of the microspherocytes
Symptomatology:
Mild anemia only
Bilirubin gale stones
Osmotic fragility test - series of salt solutions of increasing concentration
sensitivity of RBC to a medium without glucose
Survival time by 51Cr (Fig. 27 – Haen 14.2)
Surface counting patterns of 51Cr-labeled RBC (Fig. 28 – Haen 14.3)
Splenectomy!
Hereditary elliptocytosis
Mild anemia, in combination with other anemizing factors only
Again a membrane defect of actin-spectrin-ankyrin skeleton
No therapy
Defects in erythrocyte metabolism
G6-PD deficiency anemia
95% of all glucose metabolism enzyme deficiencies
Triggering factors: oxidizing drugs, infections ( activation of leucocytes producing active oxygen radicals)
Favism is a unique phenomenon – fava beans (contain an oxidant L-dopa)
Measuring of the G6-PD activity in the RBC changing of the eating habits
Pyruvate kinase deficiency anemia
Embden-Meyerhof pathway, decline of ATP production, symptoms may be severe, specific enzyme assays (no other specific features), drugs not implicated in pathogenesis
Abnormal hemoglobin production
Point mutations of Hb are mostly innocent, a small fraction is pathogenic: solubility and precipitation, affinity to oxygen, unstability of quaternal structure and Hb denaturation
Sickle-cell anemia, HbC disease, HbD disease, HbE disease
See lecture on genetics
322 Acquired accelerated hemolysis
Approximately:
hereditary hemolysis factors intrinsic to the RBC
acquiered hemolysis factors extrinsic to the RBC
Physiological aging of RBC their defense mechanisms intravascular hemolysis or phagocytosis in mononuclear phagocytes (MF, reticular and endothelial cells). The environmental stressing factors shorten the RBC life span further. They are present to a degree already under physiologic conditions in most people. These physiological/pathophysiological factors are of chemical, physical or immunological nature. The boundary between physiological and pathological is fuzzy here:
- AB0 incompatibility is present in 23% of all gestations (hemolysis is very uncommon here, however)
- Paroxysmal nocturnal hemoglobinuria is rather common (mild hemolysis)
- Metabolic stress is ubiquitous
3221 Activation of the immune system immunohemolytic anemia
Classification of immunohemolytic anemia (IHA)
Alloantibodies hemolytic disease of the newborn (HDN)
AB0
Rh
Autoantibodies
Warm-active antibodies
Cold-active antibodies
Alloantibodies
AB0 incompatibility
Mother 0 has antibodies against A and B already spontaneously (in contradisticition to Rh- mothers, in whom the antibodies not are formed before the first parturition), and these reach the foetus via placenta. Not easily, however – they are IgM, therefore large molecules, so the symptoms are mild
Antigen-antibody complexes complement activation premature lysis of RBC
Rh incompatibility – (Fig. 29 = obr. Haen 15.2)
15% of Rh- mothers
At the first parturition, the RBC penetrate from the foetus into the mother production of anti-Rh+-antibodies. The RBC having penetrated during the parturition could be killed by timely administration of anti Rh+ antibody (RhoGAM).
In the next gravidity, small numbers of the fetal RBC may get into the maternal circulation anamnestic response higher antibody titers of IgG (readily pass the placenta) HDN in the foetus
Symptoms:
Hemolysis erythroblastosis
Inability to conjugate bilirubin jaundice (possibly s.c. kernikterus, into the basal ganglia)
Residual concentration of the mother´s antibody after birth slowering of growth; exchange transfusion
Autoantibodies autoimmune hemolytic anemias (AIHA)
Warm type AIHA
IgG against RBC membrane antigens
Types:
Idiopathic – antibodies against the proper RBC are formed. Common autoimmunity mechanisms could be considered:
- Molecular mimicry with some microbe
- Lowered function of TS production of antibodies
- Polyclonal B cell activation
- Enhanced presentation of antigens etc.
Drug induced (Fig. 30 = obr. Haen 15.5)
The drug is a hapten and in a complex with a carrier protein production of antibodies. Three possibilities:
- a drug with a surface RBC antigen neoantigen production of antibodies and opsonization, e.g., penicillin
- a drug and serum protein (instead of RBC protein) neoantigen
complexes are deposited on RBC membrane, e.g., antimalarics, sulfonamides, phenacetin
Alfa-methyldopa (antihypertensive drug) triggers the gene for the Rh factor
With other diseases: leukemias, SLE, inf. mononukleosis
Pathogenesis of warm type AIHA (Fig. 31 = obr. Haen 15.4):
RBC coating with an antibody = opsonization binding of MF on RBC pitting by means of nipping of RBC sphericity loss of flexibility trapping
Opsonization rarely leads to intravascular hemolysis
Symptoms of warm-type AIHA:
Are mild, hemolysis is compensated
Pitting spherocytes, microcytes
Direct Coombs test (Fig. 32 = obr. Haen 15.8): Antiserum against anti-RBC antibodies is formed in rabbits RBC agglutination. IgG alone cannot bridge the repulsive force between RBC (= zeta potential), IgG + anti-IgG antibody can do it agglutination
Therapy: corticosteroids, immunosuppresive drugs
Cold type AIHA
IgM against s.c. I antigen on the RBC surface, present also normally. IgM bridge
the zeta potential they activate complement easily
Etiology:
Enhanced anti-I antibodies
- idiopathic
- in infectious diseases (cause unknown): mycoplasma, inf. mononucleosis, lymphoproliferative diseases
Patogenesis:
cooling I antigens are better accessible to the antibodies
Complexes on RBC complement activation
C3b fragment intravascular hemolysis and agglutination
Symptoms:
Anemia only mild, but the blocking of small extremity and acral vessels painful blanching of the skin
The withdrawn blood agglutinates spontaneously in the room temperature
3222 Physical factors red cell fragmentation syndromes
Etiology:
a) Long-distance running or marching (intravascular destruction of the RBC in the microcirculation of the feet due to the repeated crashes of the soles with hard surfaces – march hemoglobinuria)
b) Artificial heart valves - traumatic cardiac hemolytic anemia. Schistocytes often present (sickles)
c) Vasculitis or disseminated intravascular coagulation (DIC production of multiple intravascular thrombi) the blood is driven through the narrowed vessels mechanical damage to RBC
3223 Chemical agents
Various forms of hemolytic anemia
Lead, copper salts, nitrobenzene, aniline, naphtalene
Aspirin, phenacetin, antimalarics, sulfonamides…
In high doses, they damage not only the G6-PD defective RBC, but also normal ones
Natural poisons (spiders, insects, snakes)
3224 Microorganisms
Various forms of anemia (e.g., anemia of malaria)
Multiply in the RBC – genus Plasmodium
Lyse the membrane – Clostridium welchii
Produce polysaccharides which are adsorbed to RBC antibodies
3225 Secondary to other diseases
Various forms of anemia (e.g., anemia of hepatic failure) Many inflammatory and malignant diseases
Renal failure – echinocytes (burr cells)
Hepatic diseases
3225 Sensitivity to complement paroxysmal nocturnal hemoglobinuria
Unknown factor (somatic mution?) complement activation in the RBC membranes (by the alternative way)
Pancytopenia
Loss of Fe via urine
Venous blood clots
Testing: a small quantity of complement lyses RBC
Dostları ilə paylaş: |