rev:February 3, 1997
Return (Index/Home Page)
Return (IgG Subclass Kits)
Return ( IgG
Subclass Book Table of Contents)
The following book on the IgG Subclass is made available by the permisssion
of CLB Reagents (Netherlands). It is for your personal use and may not be
reproduced without the permission of CLB Reagents. This material is for
information use only and should not be construed as medical advice. We are
not responsible for any misprints or error or ommissions. Certain charts
,graphs and table have been ommitted or changed in style (not content)
to fit this web site. Please use this information as part of your discussion
with your medical professional.
2.4 Antibody activity of IgG subclasses
The IgG subclass distribution in specific antibody responses has been found
to vary with structure of the antigen (nature of carrier, number and nature
of the epitopes, physicochemical properties), its dose and route of entry,
as well as with genetic constitution of the host. In contrast to T
cell-independent (thymus-independent) antigens,T cell-dependent thymus-dependent)
antigens require interaction with helper T lymphocytes in order to stimulate
B lymphocytes to antibody production.Interestingly,stimulation of antibody
responses towards certain antigens may result in a selective increase in
IgG antibodies of certain subclasses (34,35,36). Whereas antibodies against
bacterial and viral protein antigens such as tetanus toxoid or outer-membrane
components,which are T cell-dependent antigens, can be detected in all four
IgG subclasses, IgG1 is the prevailing isotype, sometimes in combination
with IgG3(37). Anti-protein antibodies of the IgG2 subclass generally provide
only a marginal contribution. On the other hand, IgG antibodies against
polysaccharide antigens,which are generally T cell-independent,generally
show a much more pronounced subclass distribution: immunization with several
encapsulated bacteria leads to an almost exclusive IgG2 anti-polysaccharide
response (38). An exception is seen in children under the age of 2-3 years,in
whom anti-polysaccharide antibodies have been found to occur in the IgG1
subclass (39).
Repeated, long-term antigenic stimulation with T cell-dependent antigens
may lead to a marked IgG4 antibody response(40). In general, anti-viral IgG
antibodies are highly restricted to IgG1 and IgG3, with IgG3 antibodies appearing
first in the course of infection. The IgG subclass distribution in an
anti-bacterial response will be more heterogeneous, since bacteria contain
many different antigenic epitopes,with considerable variations in their protein
and carbohydrate structures.
The IgG subclass determination of antigen-specific antibodies is still quite cumbersome,although many studies are performed in this area. As a major drawback, no generally accepted international age-related reference values are available. Moreover, different assay systems do not always provide consistent results. The antigen-specific antibodies are mostly determined by means of ELISA, the antigen being coated on a microtiter plate,followed by incubation with the antibodies to be characterized, and finally with enzyme-labelled monoclonal anti-IgG subclass-specific antibody.
Return ( IgG
Subclass Book Table of Contents)
Return (IgG Subclass
Kits)
HOME (index Page)
RDI Divison of Fitzgerald Industries Intl
34 Junction Square Drive
Concord MA 01742-3049
USA
phone (978) 371-6446 or (800) 370-2222
fax (978) 371-2266
EMAIL:antibodies@fitzgerald-fii.com