a measure of the severity of the inflammatory process, especially in virally induced chronic liver disease, chronic bacterial infections, collagen vascular diseases and other

 Immunocompetent persons have an immune system

that can be divided into the following two functionally

cooperative but developmentally independent ways:

¾ Thymus (T) lymphocyte system; it represents a

functionally heterogeneous group of cells concerned

with immune regulation and antigen elimination

¾ Bursa or bone marrow (B) lymphocyte system; B

lymphocytes differentiate into plasma cells which

synthesize and secrete antibodies after an antigenic

stimulus.

Immunoglobulins represent a heterogeneous group of

proteins with antibody function, i.e. they are capable of

binding antigen. The structure of antigen binding site is

made according to the configuration of the antigen with

which the antibody reacts. Immunoglobulins have following effector functions:

¾ Formation of immune complexes with antigens

¾ Binding the membrane receptors of defense cells and

their activation

¾ Reaction with plasma proteins, e.g. with complement

components, and activation of these proteins in order

to eliminate the antigen.

Ig Classes

IgG, IgA, IgM, IgD and IgE are present in descending order

of concentration. IgG has subclasses from IgG1 to IgG4, IgA

and IgM have two subclasses each namely 1 and 2.

Ig Structure

Diagnostic Immunology 725

Immunoglobulin G (IgG)

Increased in Decreased in

• IgG myleoma • Acquired immunodeficiency

• Sarcoidosis • Hereditary deficiencies

• Chronic liver disease • Protein-losing syndromes

• Autoimmune diseases • Pregnancy

• Parasitic diseases • Non-IgG myeloma

• Chronic infection •  Waldenström’s

macroglobulinemia

Immunoglobulin M (IgM)

Increased in Decreased in

• Liver disease • Hereditary deficiency

• Chronic infections • Acquired immunodeficiency

•  Waldenström’s

macroglobulinemia

• Protein-losing syndromes

•  Non-IgM myeloma

• Infancy, early childhood

Immunoglobulin A (IgA)

Increased in (in relation to other Ig’s) Decreased in (alone)

•  Gamma-A myeloma

(M-component)

•  Normal persons (1:700)

•  Cirrhosis of liver •  Hereditary telangictasia (80% of

patients)

•  Rheumatoid arthritis with high

titers of rheumatoid factors

•  Type III dysgammaglobulinemia

•  Malabsorption (some patients)

•  SLE (some patients) •  SLE (occasionally)

•  Sarcoidosis (some patients) •  Cirrhosis of liver (occasionally)

•  Wiskott-Aldrich syndrome •  Still’s disease (occasionally)

•  Other rare entities •  Recurrent otitis media

(occasionally)

•  Non-IgA myeloma

•  Waldenström’s

macroglobulinemia

•  Acquired immunodeficiency

(combined with other Ig’s)

•  Agammaglobulinemia

Acquired

Primary

Secondary (multiple myeloma,

leukemia, nephritic syndrome,

protein losing enteropathy)

Congenital

Hereditary thymic aplasia

Type I dysgammaglobulinemia

(all, IgG, IgM, and IgA decreased)

Type II dysgammaglobulinemia

(IgA and IgM absent, IgG has

normal levels)

•  Infancy, early childhood

Serum Immunoglobulin Changes in Various Diseases

Disease IgG IgA IgM

Immunoglobulin disorders

Lymphoid aplasia D D D

Agammalglobulinemia D D D

Type I dysgammaglobulinemia

(selective IgG and IgA deficiency)

D D N or I

Type II dysgammaglobulinemia

(absent

N D D

IgA and IgM)

IgA globulinemia N D N

Ataxia telangiectasia N D N

Hematological neoplasms

Heavy chain disease D D D

IgG myeloma I D D

IgA myeloma D I D

Macroglobulinemia D D I

ALL N D N

CLL D D D

AML N N N

CML N D N

Hodgkin’s disease N N N

Liver disease

Hepatitis I I I

Laennec’s cirrhosis I I N

Biliary cirrhosis N N I

Hepatoma N N D

Miscellaneous

Rheumatoid arthritis I I I

SLE I I I

Nephrotic syndrome D D N

Trypanosomiasis N N I

Pulmonary tuberculosis I N N

N = normal, I = increased, D = decreased

TURBIDIMETRIC IMMUNOASSAY FOR

ESTIMATION OF IMMUNOGLOBULIN IgA IN

HUMAN SERUM

Quantia IgA

(Courtesy: Tulip Group of Companies)

Summary

Persistently elevated immunoglobulin levels indicate an

ongoing response of the immune system, whereas a decline

in immunoglobulin levels hints at a recovery from the

726 Concise Book of Medical Laboratory Technology: Methods and Interpretations infectious process. The absolute levels of immunoglobulin

concentration are a measure of the severity of the

inflammatory process, especially in virally induced chronic

liver disease, chronic bacterial infections, collagen vascular

diseases and other autoimmune diseases. In diseases that

cause hypergammaglobulinemia quantitative determi -

nation in conjunction with the clinical presentation as well

as analysis of serological and clinical chemistry results may

not only help in diagnosis, differential diagnosis, but may

also prove to be useful for disease monitoring and prognosis.

IgA is the second most abundant immunoglobulin

(approximately 10% of the total Ig mass) and is the major

immunoglobulin found in mucosal surfaces. Patients with

congenital IgA deficiency are prone to autoimmune diseases,

and may develop antibodies to IgA and anaphylaxis if

transfused. Approximately, 10 to 15% of all myeloma are of the

IgA type. Polyclonal increase in serum IgA may be observed

in chronic inflammatory disease of gastrointestinal and

respiratory tracts and liver. IgA may be decreased in patients

with chronic sinopulmonary disease, ataxia-telangiectasia

or congenital. Information regarding the concentration of

IgA can be obtained by using QUANTIA-lgA reagents.

TURBIDIMETRIC IMMUNOASSAY FOR

ESTIMATION OF IMMUNOGLOBULIN IgG IN

HUMAN SERUM

Quantia IgG

(Courtesy: Tulip Group of Companies)

Summary

Persistently elevated immunoglobulin levels indicate an

ongoing response of the immune system, whereas a decline

in immunoglobulin levels hints at a recovery from the

infectious process. The absolute levels of immunoglobulin

concentration are a measure of the severity of the

inflammatory process, especially in virally induced chronic

liver disease, chronic bacterial infections, collagen vascular

diseases and other autoimmune diseases. In diseases that

cause hypergammaglobulinemia quantitative determination in conjunction with the clinical presentation as well

as analysis of serological and clinical chemistry results may

not only help in diagnosis, differential diagnosis, but may

also prove to be useful for disease monitoring and prognosis.

Deficiency of IgG is associated with frequent and

occasionally severe pyogenic infections. Increased levels

of IgG are associated with chronic or recurrent infections,

various autoimmune disorders, lymphoid or nonlymphoid malignancies and IgG myeloma.

IgG is the only immunoglobulin to cross the placenta

and provide protection from intrauterine infections to the

fetus, and is of importance in defence against infections in

newborns.

Decreased levels of IgG are observed in agammaglobulinemia, hypogammaglobulinemia, and nephrotic syndrome.

Information regarding the concentration of IgG can be

obtained by using QUANTIA-IgG reagents.

TURBIDIMETRIC IMMUNOASSAY FOR

ESTIMATION OF IMMUNOGLOBULIN IgM IN

HUMAN SERUM

Quantia IgM

(Courtesy: Tulip Group of Companies)

Summary

The absolute levels of immunoglobulin concentration are

a measure of the severity of the inflammatory process,

especially in virally induced chronic liver disease, chronic

bacterial infections, collagen vascular diseases and other

autoimmune diseases. In diseases, that cause hypergammaglobulinemia quantitative determination in conjunction

with the clinical presentation as well as analysis of serological

and clinical chemistry parameters or test results may not

only help in diagnosis, differential diagnosis, but may also

prove to be useful for disease monitoring and prognosis.

Immunoglobulin IgM comprises approximately 7 to 10%

of normal serum immunoglobulins and are the prominent

antibody class in primary response to most antigenic

stimuli.