Lymphoid Organs and Lymphoid Cells Comparison
Immune
System | Biotechnology
The focus of today’s discussion would be the Comparison between lymphoid cells and the
lymphoid organs.
The two
major keywords of this topic are lymphoid
cells and lymphoid organs are well explained before in the previous
discussions and will guide us in better understanding of the current topic.
Please follow my posts, Cells of Immune System and Organsof Immune System, if not gone through before, this post will help you in understanding
the terms and facts and includes both ‘Cells of Immune system’ as well as ‘Organs
of Immune System’ in Biotechnology, which will be coming further in this topic.
So,
let’s start discussion on Lymphoid Cells
and Lymphoid Organs, later in
this post we will try to correctly compare both of them.
Immune
Cells or Lymphoid Cells and Immune organs or Lymphoid Organs
:
The
main cells or lymphocytes which are involved in an immune response are known as
immune cells or lymphoid cells.
The
organs which are involved in the production of immune cells and their
respective reactions are called immune
organs or lymphoid organs.
Mainly lymphoid
cells and lymphoid organs are
present only in vertebrates.
Only vertebrates possess adaptive immunity*, which is governed by antibodies and T cells.
All vertebrates have gut associated lymphoid tissue (GALT) and most of them have a
simple type of spleen and thymus.
Most Importantly, bone
marrow and lymph nodes are not present in all the vertebrates.
At cellular
level, both lymphoid cells and lymphoid organs also exhibit some differences.
Lymphocytes having antigen specific receptors on their surface are required to mount
an adaptive immune response.
Jawed
vertebrates are the only example to have B and T lymphocytes and
support adaptive immune response.
Evolutionary
Line Of Development of Lymphoid Organs and Lymphoid Cells:
The process
of evolutionary development of lymphoid organs and lymphoid cells evolved in the following
way.
·
In
Invertebrates:
Hematopoietic
stem cell give rise to phagocytes, which shows germ line
encoded pattern recognition receptors.
·
In
Jawless Vertebrates :
The hematopoietic system also produces lymphocyte like cells which
express somatically diversified antigen (Ag) receptors.
·
In
hypothetical intermediate I :
The hematopoietic stem cells also start producing a second lineage of
lymphocyte like cells, which shows structural invariant proto TCR (T cell
receptor).
·
In
hypothetical intermediate II :
Occurrence of transformation of
structurally variant proto TCR into somatically diversible VDJ type TCR through
transposon mediated insertion.
·
In
Jawed Vertebrates :
The hematopoietic stem cell finally gives rise to B lymphocytes or
cells which express somatically diversified antigen receptors.
Step by Step tabular Data on Comparative evolution of Lymphoid Organs and Lymphoid Cells:
Steps
|
Lymphoid Cells
|
Lymphoid Organs
|
I
|
Myeloid cells including
phagocytes
|
Myeloid tissue
|
II
|
Myeloid cells with B lymphocyte like cells
|
Lympho- myeloid tissue (spleen)
|
III
|
Addition of proto T cells
|
Lympho- myeloid tissue (spleen and thymus )
|
IV
|
T cell expressing modern TCR (T cell receptor)
|
Lympho- myeloid tissue ( bone marrow or equivalent and thymus)
|
V
|
T cell expressing modern TCR (T cell receptor) and B cells express modern BCR (B cell receptor)
|
Lympho- myeloid tissue ( bone marrow and thymus)
|
The above information gives you a better
understanding on the evolution of lymphoid
organs and lymphoid cells and a
better and easy comparison between the
lymphoid organs and lymphoid cells.
I believe after reading this post, you can explain
about ‘Evolution of Lymphoid Organs and
Lymphoid Cells’ and ‘Comparison
between Lymphoid Organs and Lymphoid Cells’ by yourself now.
There
is lot more to share, Keep in touch and stay happy.
Happy
Lymphoid Organs and Lymphoid Cells Learning!!!
