Changes

!width="200"|IgD

!width="200"|IgD

!width="200"|IgE

!width="200"|IgE

!width="200"|IgG

!width="200"|[[IgG]]

!width="200"|[[IgM]]

!width="200"|[[IgM]]

|-align="middle"  

|-align="middle"  

==Variation==

==Variation==

===Subclasses===

===Subclasses===

Subclasses of the five major classes also exist. These occur in the '''heavy chains''' and are coded for by the IGH gene. For examples horses have six subclasses of the IgG immunoglobulin coded for by the genes IGHG1→ IGHG6 while cattle and sheep only have three subclasses (IGHG1→ IGHG3).

Subclasses of the five major classes also exist. These occur in the '''heavy chains''' and are coded for by the IGH gene. For examples horses have six subclasses of the [[IgG]] immunoglobulin coded for by the genes IGHG1→ IGHG6 while cattle and sheep only have three subclasses (IGHG1→ IGHG3).

* Within the IgG class there are several subclasses depending on the species

* Within the [[IgG]] class there are several subclasses depending on the species

** Humans and rodents have four IgG subclasses

** Humans and rodents have four [[IgG]] subclasses

** Dogs have three subclasses

** Dogs have three subclasses

** Ruminants have two or three subclasses

** Ruminants have two or three subclasses

**** Different heavy chains are associated with different classes of antibody

**** Different heavy chains are associated with different classes of antibody

***** '''μ chain - [[IgM]] '''

***** '''μ chain - [[IgM]] '''

***** '''γ chain -IgG'''

***** '''γ chain -[[IgG]]'''

***** '''ε chain - IgE'''

***** '''ε chain - IgE'''

***** '''α chain - IgA'''  

***** '''α chain - IgA'''  

* There are also two possible light chains

* There are also two possible light chains

** There are no functional consequences for either type

** There are no functional consequences for either type

* The IgG antibodies produced in both primary and secondary responses originate from the same clones of B-cells as the [[IgM]] antibodies

* The [[IgG]] antibodies produced in both primary and secondary responses originate from the same clones of B-cells as the [[IgM]] antibodies

* The different antibody classes have the same variable domain combinations, and therefore the same antigenic specificity

* The different antibody classes have the same variable domain combinations, and therefore the same antigenic specificity

** Under the influence of T-cells, B-cells undergo immunoglobulin heavy chain switch

** Under the influence of T-cells, B-cells undergo immunoglobulin heavy chain switch

*** The B-cells mature from [[IgM]] to IgG producers

*** The B-cells mature from [[IgM]] to [[IgG]] producers

* IgE and IgA producers can be generated

* IgE and IgA producers can be generated

** These immunoglobulins tend to be produced within lymphoid tissue associated with mucosal surfaces

** These immunoglobulins tend to be produced within lymphoid tissue associated with mucosal surfaces