Hematopoiesis: Lymphoid and Monocytic Series Vocabulary

Vocabulary flashcards covering the hematopoiesis of lymphoid and monocytic series, including cell markers, maturational stages, morphological traits, and tissue-specific macrophage designations.

Lymphocyte Recirculation

The process by which lymphocytes move freely between the blood and lymphoid tissues, enabling contact with foreign blood-borne antigens and dispersing memory lymphocytes throughout the lymphoid system.

Natural Killer (NK) Cells

A major class of lymphocytes directly derived from the common lymphoid progenitor stem cell that form part of the innate immune system by directly killing infected or tumor cells, comprising $4\text{-}29\times10^0$% of blood lymphocytes.

Interleukin-1 (IL-1) and Interleukin-6 (IL-6)

Cytokine growth factors that influence the differentiation of pluripotent stem cells into lymphoid stem cells.

Central / Primary Lymphatic Organs

Organs where the initial steps of lymphocyte development occur, specifically the bone marrow and the thymus.

Thymus

A central lymphatic organ located in the anterior mediastinum that is larger in infants and children and slowly involutes with age.

Peripheral / Secondary Lymphatic Organs

Organs where lymphocytes migrate to from primary lymphatic organs to undergo proliferation or further development upon antigenic stimulation, including the spleen, lymph nodes, tonsils, and MALT.

Mucosa-Associated Lymphoid Tissue (MALT)

Secondary lymphatic structures located in mucosal membranes, such as Peyer's patches in the intestines.

CD138

The most widely known cell surface marker used to identify plasma cells.

CD4+ T Lymphocytes

T helper cells that, upon activation, secrete substances assisting B lymphocytes to differentiate into memory and effector cells; these cells are the primary target of HIV.

CD8+ T Lymphocytes

T cytotoxic cells that secrete cytotoxic substances to directly kill target cells.

Lymphoblast

The earliest morphologically identifiable cell of the lymphocytic series in the bone marrow, measuring $10\text{-}22\text{ }\frac{}{\text{}}\text{ }\nu\text{m}$ (or $15\text{-}20\text{ }\nu\text{m}$) with an N:C ratio of $7:1$ to $4:1$, fine lacy chromatin, 1-2 prominent nucleoli, and agranular dark blue cytoplasm.

Prolymphocyte

A lymphoid precursor measuring $15\text{-}18\text{ }\nu\text{m}$ with an N:C ratio of $4:1$ to $3:1$, highly condensed reddish-purple chromatin, 0 to 2 nucleoli, and medium blue cytoplasm with a thin darker blue rim and occasional azurophilic granules.

Mature Lymphocyte

The primary lymphoid cell normally seen in peripheral blood, measuring $7\text{-}15\text{ }\nu\text{m}$, featuring dense coarse clumped chromatin, no visible nucleoli, and sky blue to deep blue cytoplasm.

Variant / Reactive Lymphocyte

Antigenically stimulated mature lymphocytes with increased DNA and RNA activity seen in viral conditions like infectious mononucleosis, characterized by an overall larger size ($10\text{-}25\text{ }\nu\text{m}$ or $16\text{-}30\text{ }\nu\text{m}$), abundant foamy cytoplasm, and cytoplasmic indentation by adjacent RBCs.

Plasma Cell

A fully differentiated B lymphocyte measuring $14\text{-}20\text{ }\nu\text{m}$ responsible for antibody secretion, characterized by a small eccentric nucleus, cartwheel chromatin pattern, intense dark blue cytoplasm, and a perinuclear hof.

Hof

A visible lighter-staining area in the cytoplasm adjacent to the nucleus in plasma cells, corresponding to the location of the Golgi apparatus.

Russell Bodies

Acidophilic, refractile cytoplasmic globule inclusions seen in plasma cells that represent stored gamma globulin secretions.

Monocytes

Leukocytes that make up $2\text{-}11\times10^0$% of circulating white blood cells (up to $1.33 \times 10^9\text{/L}$) that act as phagocytes in blood and tissues.

Granulocyte-Monocyte Progenitor (GMP)

The common progenitor stem cell in the bone marrow that gives rise to both neutrophil and monocyte lineages.

Macrophage Colony-Stimulating Factor (M-CSF)

The primary cytokine responsible for directing the growth, development, and differentiation of monocytes.

Monoblast

The earliest monocytic precursor measuring $14\text{-}20\text{ }\nu\text{m}$ (or $12\text{-}20\text{ }\nu\text{m}$) with an N:C ratio of $4:1$ to $1:1$, fine distinct chromatin, 1-5 nucleoli, and agranular blue-gray cytoplasm.

Promonocyte

A monocytic precursor cell measuring $12\text{-}18\text{ }\nu\text{m}$ (or $12\text{-}20\text{ }\nu\text{m}$) featuring a slightly indented or folded nucleus, delicate chromatin, at least 1 apparent nucleolus, and scattered azure granules providing a ground-glass appearance.

Mature Monocyte

A large peripheral blood leukocyte ($12\text{-}18\text{ }\nu\text{m}$) with fine lacelike chromatin, a horseshoe-shaped or folded nucleus, blue-gray cytoplasm with fine azure granules, pseudopods, and vacuoles.

Kupffer Cells

Resident tissue macrophages located in the liver.

Alveolar Macrophages

Resident tissue macrophages located in the lungs.

Osteoclasts

Specialized resident macrophages located in bone tissue.

Microglia

Resident tissue macrophages located in the brain.

Langerhans Cells

Resident tissue macrophages located in the skin.