Transcript MLAB 1315- Hematology Fall 2007 Keri Brophy

MLAB 1415- Hematology
Keri Brophy-Martinez
Chapter 20:
Nonmalignant Lymphocyte
Disorders
Review
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Lymphs originate primarily from bone
marrow and thymus
Secondary organs include spleen,
lymph nodes, tonsils, and Peyer’s
patches in GI tract
Review
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3 general
populations
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B- lymphs: 10-20 %
T-lymphs: 60-80%
NK: < 10%
Pluripotent Stem cell
Lymphocyte Stem cell
B-cell
T-cell
Characteristic Cell
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Reactive lymphocyte - transformed or benign lymph
 Familiar terms are immunocytes, transformed
lymph, immunoblast, plasmacytoid, Downey cell
Why causes them?
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Virus attaches to the B- lymphocyte and infects it
This binding “activates” the lymphocyte causing it to
express an activation marker (CD23)
CD23 is the receptor for the B-lymph growth factor
Once the virus is inside the cell, it incorporates itself into
the B-cell genome to make more viral proteins, and keep
passing itself on to future B-lymphs
Cell Characterisitcs
Reactive Lymph
Normal Lymph
9-30 µm
8-12 µm
Cytoplasm
Abundant
Colorless to dark blue
Azurophilic granules
Can scallop the RBCs
Scant
Colorless to light blue
Nucleus
Elongated, irregular
Round
Chromatin
Coarse to moderately
fine
Coarse
Nucleoli
Absent to distinct
Absent
Size
N:C ratio
Introduction
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Majority of disorders affecting
lymphocytes are acquired
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Hallmark: reactive lymphocytosis
Reactive process
Congenital disorders
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Defect is found within lymphocytic system
Introduction
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Important to differenciate benign conditions
associated with lymphocytosis from malignant
lymphoproliferative disorders
 How?
 Presence of reactive lymphs
 Positive serological test for antibodies against
infectious organisms
 Absence of anemia and thrombocytopenia
 All of above favor a benign diagnosis
Lymphocytosis
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Excess of lymphocytes in the blood.
Absolute lymphocyte count (ALC) > 4.8 x 109 /L in adults
Relative count > 35-45%
Self-limited
Reactive process is due to infection or inflammatory conditions
B and T cells involved
Lymphocytes develop in response to antigenic stimulation.
They become “activated”
Causes of Reactive Lymphocytosis
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Infectious mononucleosis (IM)
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Caused by the Epstein-Barr Virus (EBV) which enters the body
via saliva (“kissing disease”)
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Clinical symptoms
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Classic triad: fever, pharyngitis and lymphadenpathy
Dysphagia
General malaise
Fatigue
Spleen is enlarged and nodes are firm but not tender or warm
Generally seen in children and young adults (17-25 yrs old)
Lab features of IM
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CBC
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Relative lymphocytosis
 Peaks at 2-3 weeks of infection, remains elevated for
2-8 weeks
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Leukocyte count 12-25 x 109/L
Peripheral smear
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Typical lymphocyte is historically referred to as a Downey
cell with irregular cytoplasmic border, increased cytoplasm
and dark blue edge around the periphery of the cytoplasm.
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>20% reactive lymphs
Serologic test
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Heterophil antibody test (i.e Monospot)
Causes of Reactive Lymphocytosis
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Toxoplasmosis
 Infection with intracellular protozoan
Toxoplasma gondii
 Acquired infections in children and adults
due to ingestion of oocysts from cat feces
or undercooked meat
 Can be transmitted via placenta
Causes of Reactive Lymphocytosis
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Cytomegalovirus (CMV) Infection
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Belongs to herpes family
Endemic worldwide
Acquired through transfusions, sexual
contact and close contact
Can be transmitted across placenta
Poor prognosis for immunocompromised
individuals who contract virus
Causes of Reactive Lymphocytosis
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Infectious lymphocytosis
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Affects children
Viruses include adenovirus, coxsackie A
and Bordetella pertussis
Leukocytosis and lymphocytosis occur in
first week of illness then return to normal
Lymphocytopenia
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Absolute lymphocyte count< 1.0 x 109/L
Causes
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Decreased production or increased destruction of
lymphocytes
Changes in lymphocyte circulation patterns
Other unknown causes
Refer to page 411, table 20-4
Immune Deficiency Disorders
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Impaired function of one or more of the
components of the immune system: T,
B, or NK lymphocytes
Body unable to mount an adaptive
immune response
Can be acquired or congenital
Acquired Deficiencies
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Acquired immune deficiency syndrome
(AIDS)
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Infection with a retrovirus, human
immunodeficiency virus type-1 (HIV-1)
Transmission through sexual contact or
contact with blood and/or blood products
Congenital Deficiencies
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Decrease in lymphocytes and
impairment in either cell-mediated
immunity (Tcells), humoral
immunity(Bcells) or both
Lymphocytes appear normal on ps
Congenital Deficiencies
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Severe Combined immunodeficiency Syndrome
 Major qualitative immune defects involving both
humoral and cellular immune functions
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Wiskott-Aldrich Syndrome
 Patients have recurrent infections due to
immunodeficiency, thrombocytopenia and
eczema