Isotype

noun

1. A biological specimen or other element that is a duplicate of the holotype.
2. Any of the subclasses of immunoglobulins defined by the chemical and antigenic characteristics of their constant regions.
3. In <em>zoögeog.</em>, a form common to two or more countries: applied to representatives of the same genus or family occurring in different countries.
4. A <xref>marker</xref> corresponding to an <xref>antigen</xref> found in all members of a subclass of a specific class of <xref>immunoglobulins</xref>