Immunology (elective)
MLIM-101
Prepared by:
Dr. Mohamed S. Abdel-Latif
Immunoglobulin:
Isotypes, Allotypes and
Idiotypes
Learning Outcome:
At this time you should know the following:
1. To explain the structural basis for immunoglobulin
isotypes, allotypes and idiotypes.
2. To describe some of the uses of isotypes, allotypes and
idiotypes.
Immunoglobulin Isotypes
• Definition - Antigenic determinants that
characterize the classes and subclasses of
heavy chains and types and subtypes of
light chains
Immunoglobulin Isotypes
Human IgM
antiserum
Reacts with
IgM, IgG, IgA, IgD, IgE
??
React with IgG, IgA, IgD and IgE
Absorbed antiserum
?? only with IgM
Reacts
Recognizes ??
determinants
specific for  heavy chains
(isotypes)
Immunoglobulin Isotypes
•
•
•
•
Definition
Location
Occurrence
Importance
– Ig levels
– B cell tumors
– Immunodeficiencies
IgG1 (kappa)
IgM (kappa)
Immunoglobulin Allotypes
• Definition - Antigenic determinants specified
by allelic forms of the Ig genes
– Source of antiallotypic Abs
• Location
• Occurrence
IgG1 (kappa)
IgG1 (kappa)
Person 1
Person 2
Human Immunoglobulin Allotypes
• Nomenclature
– G1m(3)
– Km(1)
Domain
IgG1
CH1
G1m(f) = (3)
Arg
214
CH1
G1m(z) = (17) Lys
214
CH3
G1m(a) = (1)
355-358
CL
Km(1)
Arg, Asp,
Glu, Leu
Val, Leu
CL
Km(3)
Ala, Val
153, 191

light
chain
Allotype
Amino
Acid
Chain
Position
153, 191
Human Immunoglobulin Allotypes
• Genetics (alleles)
– Co-dominant
autosomal genes
Domain
IgG1
CH1
G1m(f) = (3)
Arg
214
CH1
G1m(z) = (17) Lys
214
CH3
G1m(a) = (1)
355-358
CL
Km(1)
Arg, Asp,
Glu, Leu
Val, Leu
CL
Km(3)
Ala, Val
153, 191
Km(1)/Km(3) X Km(1)/Km(1)
Km(1)/Km(1) and Km(1)/Km(3)
– Allelic exclusion

light
chain
Allotype
Amino
Acid
Chain
Position
153, 191
Human Immunoglobulin Allotypes
• Genetics
(pseudoalleles)
– Co-dominant
G1m(17)
214
Domain
IgG1
CH1
G1m(f) = (3)
Arg
214
CH1
G1m(z) = (17) Lys
214
CH3
G1m(a) = (1)
355-358
CL
Km(1)
Arg, Asp,
Glu, Leu
Val, Leu
CL
Km(3)
Ala, Val
153, 191
G1m(1)
355-358

light
chain
Allotype
Amino
Acid
Chain
Position
153, 191
Immunoglobulin Allotypes
•
•
•
•
Definition
Location
Occurrence
Importance
– Monitoring bone marrow grafts
– Forensic medicine
– Paternity testing
Immunoglobulin Idiotypes
• Definition - Unique antigenic determinants
present on individual antibody molecules or
on molecules of identical specificity
Immunoglobulin Idiotypes
DNP-BSA
Strain A
Mouse
Anti-DNP Ab
Ab against
combining site??of
anti-DNP Ab
Strain A
Mouse
Purified
anti-DNP Ab
Antigenic
determinants
created by the
HVR = Idiotypes
Immunoglobulin Idiotypes
• Definition
• Location
IgG1 (kappa)
IgG1 (kappa)
Person 1
Person 1
anti-A
anti-B
Immunoglobulin Idiotypes
• Definition
• Location
• Importance
– V region marker
– Regulation of immune responses
Regulation by Id/anti-Id
+
+
Ag
Id
anti-Id
-
anti-anti-Id
-
Immunoglobulin Idiotypes
• Definition
• Location
• Importance
– V region marker
– Regulation of immune responses
– Vaccines
Anti-Idiotype Vaccines
+
Ag
Id
+
anti-Id
-
Ag
Id
anti-Id
Immunoglobulin Idiotypes
• Definition
• Location
• Importance
–
–
–
–
V region marker
Regulation of immune responses
Vaccines
Treatment of B cell tumors (T cell)
Assignment:
As a part of the semester activity,
group of students are selected every
week to prepare a short seminar about
his/her point of interest in one of the
lecture topics. That to be discussed
and evaluated during the next lecture.