Blood Cells

Question 1

neutrophils (first aid)

Answer 1

*acute inflammatory response cells
*phagocytic
*MULTILOBED NUCLEI (3-5 lobes)
*specific granules contain inflammatory mediatiors
*inflammatory states (e.g. BACTERIAL INFECTIONS) cause neutrophilia & changes in neutrophil morphology, such as left shift

Question 2

left shift (first aid)

Answer 2

*increased neutrophil precursors (bands, metamyelocytes) in peripheral blood (note - NO BLASTS)
*reflects states of increased myeloid proliferation (e.g. infection, CML)

Question 3

hypersegmented neutrophils (nucleus has 5-6+ lobes) are seen in ?

Answer 3

vitamin B12/folate deficiencies (megaloblastic/macrocytic anemia)

Question 4

erythrocytes (first aid)

Answer 4

*aka RBCs
*carry O2 to tissues and CO2 to lungs
*anucleate and lack organelles
*BICONCAVE DISCS with large surface area-to-volume ratio for rapid gas exchange

Question 5

reticulocytes (first aid)

Answer 5

*immature RBCs
*larger than RBCs
*increased reticulocytes in peripheral blood indicate erythroid proliferation
*bluish color on Wright-Giemsa stain

Question 6

thrombocytes/platelets (first aid)

Answer 6

*involved in primary hemostasis
*anucleate, small cytoplasmic fragments derived from megakaryocytes
*contain dense granules & alpha granules

Question 7

monocytes (first aid)

Answer 7

*found in blood; differentiate into macrophages or dendritic cells in tissues
*large, kidney-shaped nucleus; extensive “frosted glass” cytoplasm

Question 8

macrophages (first aid)

Answer 8

*phagocytose bacteria, cellular debris, and senescent RBCs
*differentiate from circulating blood monocytes; activated by IFN-gamma
*can function as antigen-presenting cells via MHC II

Question 9

dendritic cells (first aid)

Answer 9

*highly phagocytic antigen-presenting cells (APCs)
*function as link between innate and adaptive immune systems (via T-cell stimulation)
*express MHC class II and Fc receptors on surface
*can present exogenous antigens on MHC class I

Question 10

eosinophils (first aid)

Answer 10

*defend against helminthic (parasitic) infections
*bilobed nucleus
*packed with large eosinophilic (PINK) granules

Question 11

basophils (first aid)

Answer 11

*mediate allergic reactions
*densely basophilic (blue) granules
*contain heparin & HISTAMINE (vasodilator)
*leukotrienes synthesized and released on demand

Question 12

mast cells (first aid)

Answer 12

*mediate local tissue allergic reactions
*contain basophilic granules
*involved in TYPE 1 HYPERSENSITIVTY REACTIONS
*activated by tissue trauma, C3a and C5a, surface IgE cross-linking by antigen → degranulation → release of HISTAMINE, heparin, tryptase, and eosinophilic chemotactic factors

Question 13

lymphocytes (first aid)

Answer 13

*B cells, T cells, and natural killer cells
*round, densely staining nucleus with small amount of pale cytoplasm

Question 14

natural killer cells (first aid)

Answer 14

*important in innate immunity, especially against intracellular pathogens
*cytoplasmic lytic granules contain PERFORIN & GRANZYMES → act on target cells to induce APOPTOSIS when released

Question 15

B cells (first aid)

Answer 15

*mediate HUMORAL immune response (part of adaptive immunity)
*when antigen is encountered, B cells differentiate into PLASMA CELLS (which produce antibodies) and memory cells

Question 16

T cells (first aid)

Answer 16

*mediate CELLULAR immune response (part of adaptive immunity)
*differentiate in thymus into:
-cytotoxic T cells [express CD8, recognize MHC I]
-helper T cells [express CD4, recognize MHC II]
-regulatory T cells

Question 17

plasma cells (first aid)

Answer 17

*mature B cells that produce large amounts of antibody specific to a particular antigen
*found in bone marrow; do not normally circulate in peripheral blood