Abstract
The immunoglobulins of the chicken have been studied
with particular reference to their synthesis and function.
Since information on the physico-chemical properties
of normal immunoglobulins in the fowl was limited, the
initial part of the work was concerned with the production
of specific anti IgG and anti IgM antisera and further
characterisation studies of these proteins including gel
filtration and DEAE cellulose chromatography. Attempts
were made to isolate other immunoglobulin classes and a
third component - referred to as 7S α1 - was studied
and some of its physico-chemical properties noted. It was
not possible either by radioimmunoelectrophoresis or
antiglobulin studies to demonstrate antibody activity in this
serum component. Later, analyses of sera from bursectomised
chickens where normal amounts of 7S α1 were present also
indicated that this was not an immunoglobulin.
The experimental procedure of bursectomy was used to
study immunoglobulin synthesis and function. A method for
the surgical removal of the bursa of Fabricius in ovo was
developed and is described in detail.
Serum IgG and IgM levels in normal birds and birds
bursectomised as 17> 18 or 19 day old embryos were measured
from hatching to adulthood and three distinct patterns of
development were noted in the bursectomised birds - they
were either deficient in both immunoglobulins, deficient in
IgG with higher than normal levels of IgM or produced
substantial amounts of both Ig types. IgG and IgM levels
at 3 months of age were compared for birds bursectomised
at 17» 18 or 19 days and a significant difference was
noted in the numbers of birds deficient in IgM in the 17
day group as compared with the others. All groups showed
marked inhibition in the development of IgG synthesis.
These results are discussed in the light of current theories of the mechanism of development of immunocompetence
A long-term study of serum immunoglobulins in
bursectomised birds showed an eventual decline to
agammaglobulinaemia even in those birds with normal initial
immunoglobulin levels.
The survival rates of bursectomised birds are compared
with controls and studied in relation to immunoglobulin
status. Possible reasons for differences noted in
survival are suggested.
Specific antibody responses of normal and bursectomised
birds to bovine serum albumin, sheep erythrocytes and live
Salmonella gallinarum were measured and related to
immunoglobulin synthesis.
The receptor function of immunoglobulin molecules
on the surfaces of lymphocytes has been investigated.
Immunoglobulin determinants have been demonstrated on the
surface of bursa dependent lymphocytes but not thymus
dependent lymphocytes by the mixed antiglobulin method.
These results indicate that the surface receptors of "T"
lymphocytes may not be immunoglobulin in nature, and possible
methods for the detection and characterisation of these
receptors are suggested, and initial attempts to do so
described.
The literature on avian immune responses is reviewed
and the most important findings in the present work
discussed* Suggestions are made for further research
in various areas of the work.
