Lymphocytes Flashcards
3 types of lymphocytes circulating our blood
T cells
B cells
NK cells
T or F. Lymphocytes are polynuclear
F! mononuclear
- round, large and dark-staining nucleus
- 18-42% of circulting WBC
Lymphopenia
- decreased lymphocyte count (<1x10^9/L)
- causes: HIV, autoimmune isorders, medications
Lymphocytosis
- incrased absolute lymph count (>4.5x10^9/L)
- causes: Hep B, whooping cough, parasites, malignancies
IM
- infectious mononucleosis
- EBV
- infection occurs by contact with oral secretions
- “kissing disease”
- teens to adults
Cold Agglutinin Disease
- develops secondary to IM
- IgM autoantibodies form against “i” antigen on RBCs
- can lead to hemolytic anemia but not too severe so no treatment needed
Lymphocyte development (2)
- antigen independent: differentiate and mature in thymus and BM (1ry lymphoid organs)
- antigen dependent: lymphocytes differentiate in spleen, lymph nodes, tonsil, MALT (2ry)
Immunoglobulin gene rearrangement
during development in BM for B cells
- each produces unique antigen receptors
naive B cells leave BM and migrate to…
2ry lymphoid organs
- encounter a specific antigen and cell division occurs
- memory B cells and plasma cells produced
B lymphocyte functions
- humoral immunity by transformation into plasma cells
- present antigens to T cells
- produce cytokines to regulate T cell function
T or F. There are more B lymphocytes than T lymphs in blood
F! more T lymphs (50-85%) vs (20% B lymphs)
antigen receptor gene rearrangement for T lymphocytes
thymus (development)
NOTE: if receptor reacts with self antigens => apoptosis
when T cells encounter antigens
- activated T cells = large lymphs
- effector T cells = reactive lymphs
5-30% of lymphs
NK cells
- attack virus-infected cells and tumor cells
- large granular lymphocytes
- part of innate immune system
Clinical features of infectious mononucleosis
- fever
- pharyngitis
- lymphadenopathy
- self-limiting => symptomatic therapy
- fatigue
- splenomegaly
- complications rare: splenic rupture, neurologic complications, myocarditis, and pericarditis