Lymphocytes develop and mature through distinct stages in primary and secondary lymphoid tissues. In primary tissues like the bone marrow and thymus, lymphocyte progenitors undergo lineage commitment and maturation. A small percentage then migrate to secondary tissues like lymph nodes and spleen where antigen stimulation drives proliferation. T cells mature in the thymus while B cells mature in the bone marrow, undergoing gene rearrangement and expressing specific surface markers at different stages to eventually produce mature, circulating T and B cells. Lymphocytes recirculate between lymphoid tissues throughout the body and have varying life spans, with the majority lasting 4 years but some up to 20 years.

1. Lymphocyte Production and Maturation
PRINCESS ALEN I. AGUILAR

2. Anatomical Origin
• Primary Lymphoid
Tissue
– BONE MARROW
(B cell)-Bursa
– THYMUS (T cell)
– CD34+ HSCs (NK cell)
• undergo antigenindependent lineage
committment
• Most of the cells
produced in the primary
sites die before leaving;
only a small percentage
migrate to the secondary
tissues.
• Secondary Lymphoid
Tissue
–
–
–
–
Lymph nodes
Spleen
Tonsils
Peyer patches in the
intestine
– Weldeyer's Ring @ LN
• Proliferation of the T and
B lymphocytes in the
secondary or peripheral
lymphoid tissues is
primarily dependent on
antigenic stimulation.

3. General Stages of Lymphocyte Maturation
THEY ARE CHARACTERIZED
WITH THE USE OF
ROMANOWSKY-STAINED
FILMS: LIGHT MICROSCOPY

4. Hemocytoblast
Bone -immature cell in
Marrow
the stem cell
Lymphoid Stem
cell
-give rise to 2
distinct progenitor cells
CFU-L
-HLA-DR
-TdT
Progenitor T cell
Thymus
Progenitor B cell
α/β
Precursor T cell
Precursor B cell
ϓ/8
Precursor T cell
Periphery
Mature T cell
Centroblast
Mature B cells
Peripheral blood
Plasma Cells

5. T cell

6. B cell Maturation
Progenitor B cell
Precursor B cell
Immature B cell
Mature B cell
Activated B cell
•1st stage;No surface Ig
•w/ CD19, CD40, CD45
•rearrangement of gene
•coding for the heavy chain @ Chromosome 14
•2nd Stage
•w/ mu chain in the cytoplasm
•rearrangement of gene coding for the light chain
•Heavy chain appear w/o accompanying light chain beca
use of CALLA detection
•2 light chains
•kappa: Chrom2
•Lambda:Chrom22
•IgM on the surface
•Absence of CALLA
•w/ CD21, CD35
•CD21-receptor for Epstein Bar Virus
•IM-Infectious Mononucleosis
•Contains IgM and IgD
•Immunoglobulins G,M,A,D,E
•PRODUCED BY PLASMA CELLS

7. B cell surface markers

8. Lymphocyte
• T-cell
– LYMPHOKINES
• Tk or CTL
• Th
• Ts
• DHTL-Respond
through production of
chemotactic
lymphokines
• others:
–
–
–
–
–
–
–
CSF
MIF
LyMIG
LCF
HCSF
T-cell activator factor
HLT
• B cell
– Antibodies
•
•
•
•
•
IgG-Goes to placenta
IgM-Mega
IgA-sAliva, teArs
IgD-Don't know fxn
IgE-allergEE

9. LYMPHOKINETICS
• Is the process of the lymphocyte
maturation, multiplication, storage
and migration to tissues, including
sites of infeection or cell damage.

10. LYMPHOKINETICS
• Mitosis and
Multiplication
– Radioisotopic labeling
use for cell division,
kinetics and life span
of lymphocytes
– Pre B cells are rapidly
dividing w/in 30-36 hrs
to express B cells
specific antigens
• in peripheral blood-this
is the circulating
lymphocyte that is lack
T or B-cell surface
markers
• Life Span
• majority (78-89%) has
4 yrs life span but
some can live as long
as 10-20 yrs.
• about 11-22% of
lymphocyte are shortlived, lasting 3-4 days

11. Lymphocyte Life Span and Circulation
• When unimpeded, they are generally moves in a
characteristic manner- The nucleus is displaced forward
by an elongated tail (uropod) of cyto plasm.
– Uropod is the most adherent part of the cell
• Have to basic patterns of circulation:
– (1) recirculation of the mature, differentiated lymphocyte
continually moving from one area of lymphatic system into
another
– (2) Immature lymphocytes will travel from the BM to
Thymus and from there to the peripheral and eventually to
20 lymphoid tissue that will migrate to thymus again via
lymphatic vessels which is the long-lived T-lymphocytes.THEY MAKE UP MOST OF THE RECIRCULATING
POOL
– However it is thought that T lymphocytes has its own
pathway-it is only some @ the Lymph nodes and gut
areas

12. NORMAL REFERENCE VALUE
•
Approximately 5% of the total body lymphocyte mass is present in the circulating blood.
• 60-80% of the blood lymphocyte pool in adults is
composed of T lymphocytes and approximately
20% is composed of B lymphocytes.
•
Lymphocytes represent 31% of the total
leukocytes present at birth; within a few days of
birth, lymphocytes are the dominant type of
leukocyte in the circulation. Most of the cells are
T lymphocytes.
• In adults, lymphocytes represent approximately
34% of the total circulation of leukocytes, or 2.5
× 109/L.
Accdg. to Turgeon
Accdg. to Turgeon