A–Z of Haematology - part 6 pps

haemoglobin C a variant haemoglobinwith an amino acid substitution in thebeta chain, mainly found in those ofAfrican ancestryhaemoglobin Constant Spring avariant haemoglobin with a struc

Griscelli syndrome partial albinism

with immunodeficiency—defective

nat-ural killer cell function, absent delayed

hypersensitivity reactions and sometimes

secondary hypogammaglobulinaemia Grocott’s methenamine silver (GMS) stain a stain used for the detection offungi

growth factor a protein secreted by onecell that promotes growth of cells ofanother lineage

encoding a brain-specific homeobox

gene homologous to the Drosophila gene ‘intermediate neuroblasts defective’ (ind); GSH2 is upstream of the CHIC2- ETV6/TEL fusion gene and is dysregu-

lated in acute myeloid leukaemiaassociated with t(4;12)(q11;p13)

GTP guanosine triphosphate

guanine a purine base of DNA or RNA,

pairs with cytosine

guanine nucleotide exchange factors (GEFs) a family of molecules that bind

to inactive GTPases, e.g Rho, RAS and

RAC, and induce conformational changes

allowing GDP release and replacement

by GTP (see also RAS)

GVHD graft-versus-host disease GVL graft-versus-leukaemia

GYPA a gene at 4q28.2-q31.1, also known

as GPA and MN locus, encoding

gly-cophorin A; the M and N antigens are

encoded by alleles of GYPA

GYPB a gene at 4q28.2-q31.1, also known

as GPB and Ss locus, encoding

glyco-phorin B; the S and s antigens are encoded

by alleles of GYPB

glycophorin C and glycophorin D, which

carries the Gerbich blood group antigens

granulocyte-colony stimulating

fac-tor (G-CSF) a cytokine that promotes

granulopoiesis, leading to an increased

neutrophil count in vivo and supporting

growth of granulocyte colonies in vitro,

encoded by a gene at 17q11.2-21;

recom-binant G-CSF is available as a

colony-forming unit (GM-CFU) a progenitor

cell which can give rise to a mixed colony

of granulocytes and macrophages on in

vitro culture

granulocyte/macrophage

colony-stimulating factor (GM-CSF) a

haemopoietic growth factor, synthesized

by B cells, T cells, NK cells and

macro-phages, which stimulates production of

granulocytes and macrophages, leading

to neutrophilia and monocytosis in vivo

and sustaining growth of, mixed

granulo-cyte/macrophage colonies in vitro,

encoded by a gene at 5q31

granulocytic sarcoma chloroma, a soft

tissue tumour composed of leukaemic

myeloblasts with or without maturing

cells

granuloma (i) a cohesive cluster of

epithelioid macrophages with or without

lymphocytes and other inflammatory cells

(ii) a cohesive cluster of altered

macro-phages containing lipid vacuoles

granulomere the granular part of a

platelet

granulopoiesis the process by which

granulocytes are produced (see Fig 25,

p 95)

grey platelet syndrome an inherited

platelet defect in which platelets lack α

granules and thus, when stained, appear

pale blue or grey and agranular

GYPC 115

H4(10S170) a gene, gene map locus

10q21, encoding a leucine zipper protein

the function of which is unknown;

The leucine zipper domain is present

in the chimaeric proteins generated in

each of these cases and permits their

oligomerization

H & E haematoxylin and eosin stain

HAART highly active antiretroviral

therapy

haem a porphyrin structure that

con-tains iron and that forms part of the

haemoglobin molecule; it is synthesized

partly within mitochondria and partly in

the cytosol (Fig 34)

haematemesis the vomiting of blood

haematocrit (Hct) the proportion of a

column of centrifuged blood which is

occupied by erythrocytes or an

equiva-lent estimation produced by an

auto-mated blood counter

haematogone a primitive lymphoid cell

which morphologically resembles a

lym-phoblast but is a normal reactive cell

haematology the study of blood and its

diseases

haematopoiesis a synonym for

haem-opoiesis, this term being generally used in

the USA

haematopoietic pertaining to

haem-atopoiesis, a synonym for haemopoietic,

this term being generally used in the USA

haematoxylin a basic dye used in cytology

and to stain parasites; used in

combina-tion with eosin to stain tissue seccombina-tions

ala-dehydrase

Porphobilinogen deaminase

Uroporphyrinogen III decarboxylase

Coproporphyrinogen III oxidase

Protoporphyrinogen III oxidase

Ferrochelatase

Uroporphyrinogen III synthase

Figure 34 Haem synthesis.

The process by which haem is synthesized Enzymes are shown in italics and enzyme products in upright script.

116

haemoglobin C a variant haemoglobinwith an amino acid substitution in thebeta chain, mainly found in those ofAfrican ancestry

haemoglobin Constant Spring avariant haemoglobin with a structurallyabnormal alpha chain which is synthe-sized at a reduced rate, leading to αα

thalassaemia haemoglobin D the designation of agroup of haemoglobin variants, some αchain variants and some β chain variants,

that have the same mobility as

haemo-globin S on haemohaemo-globin electrophoresis

at alkaline pH

haemoglobin dissociation curve aplot of percentage saturation of haemo-globin against partial pressure of oxygen(Fig 37)

Haemoglobin Distribution Width (HDW) a measurement made by someautomated blood counters that indicatesthe amount of variation in haemoglobinconcentration between erythrocytes; anincreased HDW correlates with aniso-chromasia on a blood film

haemoglobin E a variant haemoglobinwith an amino acid substitution in thebeta chain, mainly found in South-eastAsia and parts of the Indian subcontinent

haemoglobin electrophoresis a thod of separating normal and variant

me-haematoxylin and eosin (H & E) the

standard stain used for staining tissue

sections, a mixture of basic haemotoxylin

and acidic eosin

haematuria the presence of red cells in

the urine

haemiglobin cyanide an alternative

designation of cyanmethaemoglobin, the

form of haemoglobin which results from

interaction with cyanide in the

cyan-methaemoglobin method for estimation

of haemoglobin concentration

haemochromatosis see hereditary

hae-mochromatosis

haemocytometer a counting chamber

for counting blood cells

haemodialysis a method of treating

acute or chronic renal failure by passing

the patient’s blood through a dialysis

machine; blood and dialysis fluid are

sep-arated by a semipermeable membrane so

that exchange of solutes can occur

haemoflagellates flagellated blood

par-asites such as trypanosomes and leishmania

haemoglobin a complex molecule

com-posed of four globin chains, each of which

partially encloses a haem molecule

(Fig 35), which has as its major function

the transport of oxygen from the lungs to

the tissues

haemoglobin A the major haemoglobin

component present in most adults,

hav-ing two α chains and two β chains

haemoglobin A 2 a minor haemoglobin

component present in adults and, as an

even lower proportion of total

haemo-globin, in neonates and infants; it has two

α chains and two δ chains

haemoglobin Bart’s an abnormal

haemoglobin with four γ chains and no

α chains, present as the major

haemo-globin component in haemohaemo-globin Bart’s

hydrops fetalis and as a minor component

in neonates with haemoglobin H disease

or alpha thalassaemia trait

haemoglobin Bart’s hydrops fetalis

a fatal condition of a fetus or neonate,

resulting from homozygosity or compound

heterozygosity for αα0 thalassaemia

(Fig 36); as there are no alpha genes

there can be no production of

Figure 35 The haemoglobin molecule.

A sketch of the haemoglobin molecule showing that

globin chains, each enclosing a haem moiety.

118 haemoglobin F

haemoglobins from each by applying a

haemolysate to a membrane or gel across

which there is an electrical gradient; the

pH and the nature of the membrane or geldetermines the rate at which differenthaemoglobins migrate in the electricalfield (Fig 38)

haemoglobin F fetal haemoglobin, themajor haemoglobin of the fetus andneonate (Fig 39), which is present as avery minor component in most adultsand in higher amounts in a minority;adult levels have usually been reached byabout one year of age

haemoglobin G the designation of agroup of haemoglobin variants, some ofwhich are alpha chain variants and some

of which are beta chain variants, that

have the same mobility as haemoglobin S

on haemoglobin electrophoresis at

alka-line pH; whether a variant haemoglobin

Acidosisincreased2,3BPGfever

kPa

Figure 37 A haemoglobin dissociation curve.

A haemoglobin dissociation curve showing the

sigmoid form of the normal dissociation curve and

the factors which shift the curve to the left or right.

Mother

α0 thalassaemiaheterozygosity

Father

α0 thalassaemiaheterozygosity

Hb Bart'shydrops fetalis

(homozygosity

for α0thalassaemia)

α thalassaemiatrait(heterozygosityfor α0thalassaemia)

α thalassaemiatrait(heterozygosityfor α0thalassaemia)

Normal

Figure 36 haemoglobin Bart’s hydrops fetalis.

A diagrammatic representation of the possible outcomes in a family at risk of

producing a fetus with haemoglobin Bart’s hydrops fetalis.

haemoglobin Lepore 119

is designated haemoglobin D or

haemo-globin G is completely arbitrary

haemoglobin Gower an embryonichaemoglobin; haemoglobin Gower 1 is

ζ2ε2and haemoglobin Gower 2 is α2ε2

haemoglobin H a variant haemoglobinwith four β chains and no α chains,

present in haemoglobin H disease and, in

small quantities, in αα thalassaemia trait haemoglobin H disease a thalas-saemic condition caused by markedunderproduction of α chains, often butnot always resulting from compound heterozygosity for αα+ thalassaemia and

αα0 thalassaemia with consequent lack of

three of the four alpha genes (Fig 40)

haemoglobin H inclusions smallround evenly dispersed erythrocyte

inclusions composed of haemoglobin H;

they can be stained with vital dyes

haemoglobin Lepore a varianthaemoglobin resulting from the fusion

of part of a δ globin gene with part of

Figure 38 Haemoglobin electrophoresis.

The results of haemoglobin electrophoresis on a

cellulose acetate membrane at alkaline pH.

Haemoglobins S, D and G move together, as do

C; ( b) haemoglobin S; (c) haemoglobins A and C;

(d) haemoglobin S; (e) haemoglobins A and C;

(f ) haemoglobins S and C; (g) haemoglobins A and

C; (AFSC) control sample containing haemoglobins

1009080706050403020100

Haemoglobin F

Figure 39 Changes if haemoglobin F percentage during development.

The proportions of haemoglobin F and other normal haemoglobins present in the

embryo, fetus, neonate and infant.

haemolytic uraemic syndrome (HUS)

a syndrome of microangiopathic

haemo-lytic anaemia and acute renal failure haemophagocytic syndrome an ill-ness resulting from haemophagocytosis,

a β globin gene, giving a δβ fusion

gene and fusion protein; it is

synthes-ized at a slower rate than the β chain

and thus is functionally equivalent to a

β thalassaemia

haemoglobinopathy an inherited

dis-order resulting from synthesis of a

structurally abnormal haemoglobin; the

term can also be used to encompass, in

addition, the thalassaemias in which

there is a reduced rate of synthesis of one

of the globin chains

haemoglobin Portland an embryonic

haemoglobin, ζ2γ2

haemoglobin S sickle cell haemoglobin,

a variant haemoglobin with a tendency

to polymerize at low oxygen tension,

causing erythrocytes to deform into the

shape of a sickle

Mother

α+ thalassaemiaheterozygosity

Father

α0 thalassaemiaheterozygosity

α thalassaemiatrait(heterozygosityfor α0thalassaemia)

Normal

Children

Figure 40 Haemoglobin H disease.

A diagrammatic representation of the possible outcomes in a family at risk of

producing a child with haemoglobin H disease.

hairy cell an abnormal B-lymphocyte

present in hairy cell leukaemia, analogous

to a late B cell

hairy cell leukaemia a chronic lineage leukaemia with neoplastic cellswhich are morphologically and immuno-phenotypically distinctive

B-hairy cell leukaemia variant a chronicB-lineage leukaemia with neoplastic cellswhich resemble the cells of hairy cell leuk-aemia morphologically but with there being differences in immunophenotypeand haematological and clinical features

Ham test see acid lysis test

HAM HTLV-I-associated myelopathy hand mirror cell a blast cell shaped like

a mirror, may be of lymphoid or myeloidlineage

Hand–Schüller–Christian disease part

of the clinical spectrum of Langerhans

cell histiocytosis haploid a description of cells with a com-plement of 23 chromosomes, one copy ofeach autosome and either an X or a Ychromosome; normal sperm and ova are

haploid but in somatic cells haploidy is

phe-of a longer DNA sequence from one phe-of apair of chromosomes

haplotype genotype of a group of allelesfrom two or more closely linked loci, e.g.the βS gene occurs in association with several different haplotypes

hapten a small antigen that becomesimmunogenic when complexed with alarger protein

HC2 a monoclonal antibody which givespositive reactions with hairy cells andoccasionally with cells of other chroniclymphoproliferative disorders

hCDCre see CDCREL

Hct haematocrit HDN haemolytic disease of the newborn HDW Haemoglobin Distribution Width heavy chain the longer of the two poly-peptide chains of a dimer, usually refers

to the heavy chain of an immunoglobulin

characterized by pancytopenia and

some-times hepatomegaly, splenomegaly and

fever, see also familial haemophagocytic

lymphohistiocytosis

haemophagocytosis phagocytosis of

haemopoietic cells and their progeny

haemophilia an inherited haemorrhagic

disorder resulting from deficiency of

fac-tor VIII (haemophilia A, resulting from a

mutation in the F8C gene) or factor IX

(haemophilia B, resulting from a

muta-tion in the F9 gene)

haemophilia A an X-linked recessive

inherited bleeding disorder (see Fig 68,

p 207) resulting from a mutation, most

often an inversion that splits the gene,

involving the F8C gene

haemophilia B an X-linked recessive

inherited bleeding disorder, previously

known as Christmas disease, resulting

from a mutation, most often a point

mutation, in the F9 gene

haemophilia B Leiden a variant of

haemophilia B, resulting from one of a

number of point mutations in the

pro-moter region of the F9 gene, in which

factor IX concentration rises at puberty

with improvement of the bleeding

tend-ency; the likely explanation is that the

mutations affect a binding region for

androgen-sensitive transcription factors

haemopoiesis the process of

produc-tion of blood cells (Fig 41)

haemopoietic pertaining to haemopoiesis

haemopoietic cell a precursor cell

giv-ing rise ultimately to granulocytes,

mono-cytes, erythrocytes and platelets

haemopoietic growth factor a protein,

often a glycoprotein, that promotes growth

and differentiation of haemopoietic cells,

e.g erythropoietin, thrombopoietin

haemorrhage bleeding; may be a

nor-mal phenomenon, e.g following injury,

or the result of an inherited or acquired

haemorrhagic disorder

haemorrhagic disease of the

new-born a haemorrhagic disorder of

neo-nates consequent on vitamin K deficiency

haemosiderin the major storage form

of iron, present in macrophages

haemostasis the process by which

haemo-rrhage is arrested

heavy chain 121

HSC

SCFFTL3LIL7

SCFFLT3LIL3IL4IL6GM-CSF

SCFIL3IL6GM-CSF

CMP

IL3GM-CSFG-CSFM-CSF

IL3, GM-CSF,G-CSF

IL3GM-CSFM-CSFGFU-

GM

G

M

GFU-MDC

IL3IL5SCFIL3IL4SCFIL3IL4SCFIL3,SCF,GM-CSFIL11,EPO

IL3,GM-CSFIL11,EPO

SCF,IL1, IL3,IL6, GM-CSF,G-CSF, TPO

SCF,IL3, IL6,IL9, IL11,GM-CSF, TPO

Eo

Baso

Mast

CFU-BFU-E

Mega

BFU- Mega CFU-E

CFU-PSC

Bi-, tri- and multipotent progenitors

Lineage committed progenitors

Abbreviations for growth factors: SCF, stem cell factor; FLT3L, FLT3 ligand; IL, interleukin; GM-CSF, granulocyte-macrophage colony-stimulating factor; G-CSF, granulocyte colony-stimulating factor; M-CSF, macrophage colony-stimulating factor; EPO, erythropoietin; TPO, thrombopoietin.

hemighost 123

helix–loop–helix see bHLH

HELLP syndrome a syndrome occurring

in pregnancy comprising Haemolysis,

Elevated Liver enzymes and Low Platelets

helper T cell a T lymphocyte that motes antigen secretion by B lympho-

pro-cytes (see type 1 and type 2 helper T cell)

(Fig 42)

hemighost an erythrocyte in which allthe haemoglobin appears retracted intoone half of the cell leaving the remainder

molecule; each immunoglobulin molecule

has two light chains (κ or λ) and two heavy

chains (γ, α, µ, ε or δ)

heavy chain disease a

lymphoprolifer-ative disorder or plasma cell dyscrasia in

which there is synthesis of heavy chain

(γ, α or µ) rather than synthesis of

com-plete immunoglobulin molecules

Heinz body an erythrocyte inclusion

composed of denatured haemoglobin,

detected by exposure to vital dyes such

HLAtype II

CD3 TCR

αβ CD4

Antigen internalized,processed andpresented

SmIg

Ag

CD79

Antigen-presenting and antibody-secreting B cell

Helper T cell

Antigen (ag)CD79

Surface membrane immunoglobulin (SmIg)Processed antigen

Figure 42 Helper T cell.

A diagrammatic representation of the interaction between a helper T cell and a B cell The B cell binds an exogenous antigen, by means of its membrane immunoglobulin–CD79a complex, and processes it to a peptide which it presents, in a groove of an HLA type II molecule, to a helper T cell The peptide, in its HLA type II context, is recognized by the CD3–T cell receptor (TCR)–CD4 complex Other specialized antigen-presenting cells (e.g macrophages and dendritic cells) can similarly present processed antigen to helper T cells Binding of the helper T cell to the B cell also involves binding of CD2 on the T cell to CD58 on the B cell CD54 is up- regulated on activated B cells and binds to CD11a/CD18 on T cells In addition, there is binding of CD28 on the

T cell to CD80 or CD86 on the B cell, giving stimulatory signals, or binding of CD152 to CD80 or CD86 on the

B cell, giving inhibitory signals CD154 (CD40 ligand) on the T cell binds to CD40 on the B cell, giving signals for somatic hypermutation and immunoglobulin class switching Signalling is bidirectional The B cell signals to the helper T cell to become activated and proliferate while the T cell signals to the B cell to mature into a plasma cell and switch from secreting IgM to secreting other classes of immunoglobulin The progeny of the helper T cell that has been activated by an antigen-presenting B cell can migrate to other tissues where they initiate a cytotoxic

or inflammatory response if they encounter target cells expressing the appropriate antigen

and elevated serum ferritin without any

elevation of serum iron concentration orany tissue iron overload; the cataractsmay be congenital or may develop duringchildhood or adult life; the underlyingdefect is in synthesis of L type ferritin,which is increased and poorly regulated

as a result of a mutation affecting the

iron-responsive element of L ferritin mRNA; serum ferritin is L type rather

than a mixture of L and H

hereditary persistence of fetal haemoglobin an inherited condition

in which fetal haemoglobin persists athigher than normal levels beyond theneonatal period

hereditary pyropoikilocytosis aninherited abnormality of the erythrocytemembrane leading to striking poikilo-cytosis and severe haemolytic anaemia,usually consequent on inheritance of two different elliptogenic mutations or

an elliptogenic mutation and a commonlow expression allele, α spectrinLELY

hereditary spherocytosis an inheritedabnormality of the erythrocyte membraneleading to spherical red cells, compensatedhaemolysis and sometimes haemolyticanaemia, resulting from mutations in

ANK1, SPTA1, SPTB, EA1 or EPB42

genes

hereditary stomatocytosis an herited abnormality of the erythrocytemembrane leading to formation of bowl-

in-shaped cells, referred to as stomatocytes

(Fig 43), and either compensated lysis or haemolytic anaemia

haemo-hereditary xerocytosis an inheritedabnormality of the erythrocyte mem-brane leading to increased cation flux and either compensated haemolysis orhaemolytic anaemia

Hermansky–Pudlak syndrome a heterogeneous inherited syndrome with

autosomal recessive inheritance

char-acterized by oculocutaneous albinismand defective platelet function, the latterresulting from a storage pool defect; some cases result from mutation of the

HPS1 gene on chromosome 10; there is

increased lipofuscin in bone marrowmacrophages

of the cell as an empty membrane;

hemighosts are characteristic of oxidant

damage and the presence of an unstable

haemoglobin

hemizygosity having a single copy of

a gene on a single X chromosome, e.g

hemizygosity for G6PD deficiency

hemizygote an individual having one

copy of a gene on a single X chromosome,

e.g a male with a singe copy of a mutant

G6PD gene

HEMPAS Hereditary Erythroid

Multi-nuclearity with Positive Acidified Serum

test—type II congenital dyserythropoietic

anaemia (see acid lysis test)

heparin a sulphated glycosaminoglycan,

a naturally occurring anticoagulant in

human and animal tissues, which inhibits

thrombin, factor Xa and activated

intrin-sic pathway coagulation factors in vivo

and in vitro; as a therapeutic product,

it has usually been extracted from pig

intestines (see also low molecular weight

heparin and unfractionated heparin)

hepatitis inflammation of the liver

hepatomegaly enlargement of the liver

HER2 see ERBB2

hereditary passed down from a parent,

usually by means of genes located on

chromosomes but occasionally by

mito-chondrial genes

hereditary elliptocytosis an inherited

abnormality of the erythrocyte

mem-brane leading to elliptical red cells,

some-times to haemolysis and occasionally to

a haemolytic anaemia, resulting from

mutations in the SPTA1, SPTB, AE1 or

EPB41 genes

hereditary glucosyl ceramide lipidosis

see Gaucher’s disease

hereditary haemochromatosis a

hereditary condition leading to iron

overload; in adults, the condition usually

results from mutation in the HFE gene

but in a minority it results from mutation

in the TFR2 gene; the juvenile form

results from mutation of a gene on

chro-mosome 1q

hereditary hyperferritinaemia–

cataract syndrome a constitutional

abnormality with autosomal dominant

inheritance, characterized by cataracts

124 hemizygosity

histidine-rich glycoprotein 125

it combines with transferrin receptor,reducing its affinity for iron; the C282Ymutation, present in most patients withhaemochromatosis, prevents the binding

of the HFE product to β2-microglobulin

high grade a term used to describeaggressive, highly malignant lymphomas

high hyperdiploid having between51–60 chromosomes

highly active antiretroviral therapy (HAART) triple-drug antiretroviraltherapy for HIV infection employing

a combination of drugs from threeclasses: (i) nucleoside-analogue reverse-transcriptase inhibitors, non-nucleoside-analogue reverse-transcriptase inhibitorsand protease inhibitors

high performance liquid raphy (HPLC) a method of separatingproteins, such as haemoglobin variants,from each other on the basis of char-acteristics such as size, hydrophobicityand ionic strength; a solution of proteins

chromatog-is passed through a specially designed column with different proteins emergingafter a characteristic period of time, refer-red to as the retention time (Fig 44)

HIP a gene, Huntingtin Interacting

Protein 1, gene map locus 7q11.2; encodes

a protein which interacts with Huntingtinand F-actin, and is involved in dopaminereceptor endocytosis at clathrin coated pits;Huntingtin is the product of the gene that

is mutated in Huntington’s disease; HIP contributes to the HIP1-PDGFRB fusion

gene in chronic myelomonocytic aemia associated with t(5;7)(q33;q11.2);

leuk-in the resultleuk-ing fusion proteleuk-in the extracellular domains of PDGFRβ arereplaced with almost the entire HIP1molecule, leading to constitutive receptoroligomerization and activation

hirudin an antithrombotic substance duced in the salivary glands of the medicinal

pro-leech, Hirudo medicinalis; recombinant

forms are desirudin and lepirudin histamine an inflammatory mediator

secreted by mast cells and basophils histidine-rich glycoprotein a plasmaprotein, synthesized by platelets, thatbinds to plasminogen, thus reducing theamount of circulating plasminogen avail-

herpesviruses a group of viruses

includ-ing chicken pox/varicella, the Epstein–

Barr virus and cytomegalovirus

herpes zoster shingles, recrudescence

of varicella-zoster virus infection, causing

a vesicular rash in the distribution of a

peripheral nerve

heterochromatin condensed, genetically

inactive chromatin

heterodimer a dimer composed of two

dissimilar polypeptide chains

heterogeneous irregularly distributed

heterophile antibody an antibody

recognizing antigens on cells of another

species

heteroplasmy the presence in a cell of

mutated and non-mutated mitochondrial

DNA

heterozygote an individual who has a

single copy of a specified autosomal or

(in a female) X chromosome gene

heterozygous having a single copy of a

specified autosomal or (in a female) X

chromosome gene

hexokinase an enzyme in the

erythro-cyte glycolytic pathway (see Fig 33, p 113)

HFE a gene on chromosome 6, mutation

of which can cause hereditary

haemochro-matosis in homozygotes and compound

heterozygotes; previously known as

HLA-H; it encodes a protein that interacts with

the transferrin receptor ( product of the

TFRC gene), negatively affecting cellular

iron uptake from transferrin; the HFE

protein binds to β2-microglobulin,

bind-ing bebind-ing essential for transport of the

HFE product to the cell surface where

Figure 43 Stomatocytes.

Three stomatocytes, showing that in three

dimensions a stomatocyte is bowl shaped.

126 histiocyte

and related lineages are designated in the

WHO classification as shown in Table 6 histiocytic lymphoma an outmodeddesignation of large cell lymphoma of B- or T-lymphocyte lineage rather than

of histiocyte lineage; to avoid confusion,

a tumour resembling a lymphoma but

able for conversion to plasmin; it

there-fore has an antifibrinolytic effect and

deficiency, which is very rare, is

asso-ciated with an increased likelihood of

thrombosis

histiocyte an alternative designation of

a macrophage; neoplasms of histiocytic

45.037.530.022.515.07.50.0

Figure 44 High performance liquid chromatography.

Separation of normal haemoglobins from each other by high performance liquid

chromatography (HPLC): (a) normal adult showing, from left to right, haemoglobin

F (shaded), glycosylated haemoglobin ( long black arrow), haemoglobin A that has

undergone post-translational modification (short black arrow), haemoglobin

left to right, haemoglobin F which has undergone post-translational modification

(short arrows), haemoglobin F (shaded), and haemoglobin A ( hollow arrow); note