Immune Hemolytic Anemias (IHA)

Definition

Classification

Mechanism of hemolysis

Characteristics in clinical and laboratory

Diagnostic process

Definition of IHA

The shortened red cells life span is caused by the antigens existing on the surface of erythrocytes reacting with relative antibodies. This acquired hemolytic anemia is termed immune hemolytic anemia.

IHAClassification

1. According to the cause of Ab production

2. According to the nature of Ab

Autoimmunehemolytic anemia (AIHA)

Drug-induced immune hemolytic anemia (DIHA)

Allo-immune hemolytic anemia (ALIHA)

temperature

Warm Ab type(37 ℃ ， IgG)

Cold Ab type (less than 37 ℃, IgM)

Mixed Ab type

I. Autoimmunehemolytic anemias (AIHAs)

Definition

AIHAs are a group of acquired hemolytic disorders that are the result of antibodies or complement binding to specific antigens on the RBC membrane, which leads to a shortened RBC life span and an increased RBC destruction.

1. IgG Warm Abs bind to RBCs at 37 but fail to aggl℃utinate the RBCs.

2. Cold agglutinins almost always are of IgM subtype and clump RBCs at cold tempratures. (CAS)

.3. Donath-Landsteiner(IgG) Abs bind to RBCs in the cold and activate the hemolytic complement cascade when the RBCs are warmed to 37 . (PCH)℃

Antierythrocyte antibodies can be divided into three general categories:

AIHA : Warm Antibody Type

overview:

•a group of diseases resulting from the binding of IgG to the RBC membrane.

• The IgG-bound RBCs either are trapped by macrophages as they pass through the spleen or may first have part of their membrane removed, then destroyed in the circulation.

• 70% of AIHAs.

Pathogenesis of hemolysis:

FcR

C3bR

macrophages37°C

IgG

Spleen sinus

spleenextravascular and/or intravascular

Idiopathic: females more than males?secondary causes:• Lymphoprolitive diseases (e.g., CLL , non-Hodgkin lymphoma )

• Connective tissue diseases(e.g., SLE)

•Immune deficiency disorders( e.g., AIDS)

•Drugs(e.g., penicillin, quinidine, methyldopa, cephalosporins)

Etiology:

1. jaundice, anemia(e.g., fatigue, shortness of breath, light-headedness) or asymptomatic

2 . PE: jaundice, splenomegaly, and some signs relate to underlying illness , such as fever, lymphadenopathy, skin rash,, hypertension, renal failure, petechiae or ecchymoses ( PC decrease)

Highly variable symptoms that are unrelated to temperature.

Evans syndrome is the combination of warm AIHA and idiopathic thrombocytopenia purpura.

Clinical Features

WBC? PC: N or low

Lab Findings

Blood ： Hb, PCV , RBC( vary from normal to low) Ret , “3M” (MCV ?) and RDW fall

Morphology ： polychromatic RBCs, macrocytosis, nucleated RBCs, or microspherocytes.

Bone marrow: hyperplasia figure

Serum bilirubin and urobilinogen(urine):elevated

DAT usually positive. ( confirm test)

•Blood smear may present macrocytes, spherocytes.

•Bone marrow reveals erythroid hyperplasia. Polychromatic and orthochromatic normoblasts increaes, M/E decreased, erythroid mitosis increased; mature RBC?

Coombs Test1. Direct Anti-immunoglobin Test ( DAT )

serum

Anti-immunoglobin

Poly-

Anti-IgG

Anti-complement

II. Cold AIHA

Cold Agglutinin Syndrome (CAS)

•a group of disorders caused by IgM auto-antibodies (usually against the I/i antigen)

• cold agglutinins bind to RBCs at cold temperatures (4 ℃ - 18 ℃).

overview

Hemolytic mechanism of CAS :

Extravascular

or Intravascular0 to 5 (4~18) ℃

agglutinate

cold agglutinins-IgM binding at low tempe

rature

anti-C3+

activate complement, and C3b fixation( at higher tempratures.)

1. Cold-induced acrocyanosis (Raynaud’s phenomenon) ：

blue color of the skin at fingertips, toes, nose, and ear lobes) due to vascular sludding arising from agglutination.

2. cold-associated hemoglobinuria

Specific clinical features of CAS

4. Symptoms worse in cold weather and higher IgM titer and activity)

3. Secondary to upper respiratory tract infection

--anemia: Hb

--Hemolysis: ret, bilirubin, LDH,

--blood smear: RBC agglutination

Lab Findings:

--bone marrow

--DAT +: for C3 only. (screening)--The Cold agglutinin test (confirm)

Coombs TestDirect Anti-immunoglobin Test ( DAT )

serum

Anti-immunoglobin

Poly-

Anti –C3 +

Patient serum cold agglutinin IgM

autoerythrocytes

or O type RBC

or the same type RBC

4 to 30 ℃ ℃

37 ℃

Cold agglutinin test

【 Result 】 Normal: titer<1:40, CAS: titer>1:64

• IgG autoantibodies are specific for the P antigen.

• D-L Ab: mono- or polyclonal; IgG;

III. Paroxysmal cold hemoglobinuria (PCH)

syphilis

• paroxysms of fever, back pain, leg pain,

abdominal cramps; rigors (after exposure to cold temp.) hemoglobinuria

• hemolysis: intravascular , less than 20 ℃• children often , secondary to viral disorder

1. Hb, PCV (severity of anemia)

2. Ret low in episode; elevated in recovery phase.

3. Blood smear: anisocytosis, poikilocytosis, polychromatophilia, spherocytes, nucleated RBCs.

4. FHb , Hp ; hemoglobinuria, methemoglobin (urin)

5 DAT negative usually, or C3 + only, IAT+

6 Donath-Landstainer Test : D-L Ab +

Lab findings:

Indirect Anti-immunoglobin Test ( IAT )

T<20 ℃

Sample of patient

Anti-IgG ， IgM or / and C

Cold Warm Hemolysis Test

(Donath-Landstainer Test)

【 Principle 】

At lower temperature(<20 ), D-L antibody ma℃y attach to the surface of the patient’s red cell. When temperature up to 37 , the red cells with D-L antib℃odies lysis rapidly with the help of activated complements.

【 Result 】 Negative: no lysis in normal people.

37 ℃

<20℃

Diagnostic process of IHA

jaundice, hemoglobinuria

Splenomegaly, fever, chilly

PLC

Coombs test

cold agglutinin test cold warm hemolysis test

CAS PCH

DAT+

titer>1:64

Anti-C3

Anemia and type of anemia

Hemolytic anemia and its type

IHAunderlying diseases and specific featrues?

Warm type of AIHA

Evan syndrome

Hb, RBC, PCV; 3M, RDW

Fatigue, weakness

Retmorphology serum and urine

Anti-C3, ITA+

Questions :

1. Summarize the features of blood and bone marrow smear in IHA?

2. How do you know the patient may have IHA?

Case

A female, 45 years old

Complaintof “having been fatigue, weakness for about 6 months. Sometimes had black urine.”

PE: moderate splenomegaly and slightly enlarged liver.

Lab: Hg 80g/l, Hct 0.30 , RBC 2.5X1012 , RDW 16.7

What do you know from these information?

Blood smear

Marrow cellularity (×100)

Marrow smear (×1000)

No.5 is the result of Coombs test of the patient

DAT(anti IgG+anti C3)

1 2 3 4 5

Discussing questions:

1. What is your primitive impression of the patient?

Describe your evidence?

2. What clinical information do you need to support your diagnosis?

3. Which further tests do you need to complete the diagnosis?

4. Why the patient had black urine.

MYELOPATHIC ANEMIAS

These anemias are due to the bone marrow infiltration or replacement by abnormal tissues such as malignant metastases, myelosclerosis, leukemia and myeloma.

Secondary anemia

Pathogenesis of myelopathic anemia:

--bone marrow damage

--hemorrhage

--hemolysis

Clinical Features

--severe anemia

--bleeding problems may occur

--splenomegaly and hepatomegaly is common

--symptoms referable to underlying disease

Lab Findings

Blood

--varying degrees of anemia (most normocytic; slightly macrocytic)

--distinct anisocytosis and poikilocytosis

--leukoerythroblastic anemia:--reticulocytosis and polychromatophilia--The WBC count may be variable--The platelet count is often low, giant, bizarre shaped with abnormal function.

What is leukoerythroblastic anemia?

The patients suffering from anemias with nucleated RBCs and immature granulocytes in the peripheral blood.

disruption of marrow sinusoids

hematopoiesis in extramedullary sitesWhy?

.Bone marrow

--The marrow aspiration may fail or show metastatic cells and so on.

--The marrow biopsy is necessary to establish the diagnosis.

Other tests:

--x-ray

--NAP

--CD

ANEMIA

贫血的病因及发病机制分类

贫 血红细胞生成减少 红细胞破坏过多 红细胞丢

失增加 骨髓造血功能障碍

造血物质缺乏或利用障碍

铁缺乏和铁利用障碍

维生素 B12或叶酸缺乏

红细胞 内在缺陷 外在异常

干细胞增殖分化障碍

骨髓被异常组织侵害

骨髓造血功能低下

免疫因素

非免疫因素

急性失血性贫血

慢性失血性贫血

微血管病性溶血性贫血

化学、物理、生物因素致溶血

脾功能亢进

各种原因致免疫性 溶血性贫血

巨幼细胞贫血等

缺铁性贫血

铁粒幼细胞性贫血等

再障，纯红再障等

骨髓增生异常综合征等

膜异常 酶异常 Hb异常

珠蛋白生成障碍性贫血

异常血红蛋白病

不稳定血红蛋白病

葡萄糖6磷酸脱氢酶缺乏症

丙酮酸激酶缺乏症等

遗传性球形红细胞增多症

遗传性椭圆红细胞增多症等

阵发性睡眠性血红蛋白尿症

肾病、肝病、感染性疾病、

内分泌疾病等

白血病、骨髓瘤、癌转移、

骨髓纤维化等

Anemia: weakness,fatigue, listlessness,palpitation, pallor jaundice, splenomegaly

MCV increase normal decrease

MCH MA IDA,SA,Thala

MCHC infection

decrease ret increase acute loss blood hypopoiesis HA (Coomb’s)

decrease PL normal IHA

infection extracellular defect intra-

WBC chronic renal disease osmotic fragility

decrease increase increase normal decrease

AA,MF AM HS,HE, G-6PD, PK Thala

PNH (ham’s) abnormalHb

Diagnostic steps of HA:

history,infection, underlying diseases,drugs,pallor,weakness

dark urine, jaundice,hepatosplenomegaly

blood film

spherocytes, autoagglutination, red cell fragments

ret increased immune assay

cold agglutinin test Coomb’s test

positive

CAS AIHA negative cold warm

hemolysis test

transfusion reaction infection, congenital syphilis

Normocytic normochromic anemia

history, underlying diseases, pallor,weakness

blood film

decrease/ increase ret increase

morphologic features acute blood loss HA

normal abnormal

secondary hypoplasia abnormal proliferation

anemia infiltration in marrow

Infection AA MDS leukemia

renal disease MF

liver disease metastatic cancer

endocrinic disease

Microcytic hypochromic anemia:

history, underlying diseases, anemia,MCV,MCH

Blood film

SI

increased normal/ increased decreased

Iron stain Hb eletrophoresis SF

HbA2,F

increased normal/ increased decreased

SA Thalasemia anemia of chronic IDA

HbC,S, D,E disorders

etc.

Differentiation of macrocytic anemias:MCV, MCH

history, anemia ,underlying diseases,

drugs,nutrition,neurologic signs, hepatosplenomegly

blood film

increased Ret normal / decreased

marrow morphology

acute blood loss HA non-MA MA

erythroblastic anemia abnormal proliferation

Alchohol poisoning MDS Folate deficiency

Liver disease VitB12 deficiency

Pernicious anemia