171Chapte

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The basics: diagnostic terms, skin anatomy, and stains

LymphocyteKey features Round dark nucleus, generally with no visible

cytoplasm B-cell lymphocytes produce antibodies and are

important for humoral immunity Natural killer (NK) cells are part of the innate

immune system T-cell lymphocytes mature in the thymus and are

important in cell-mediated immunity TH1 cells produce interleukin-1 (IL-1), IL-2, IL-12,

and interferon-gamma (IFN-) and are important for cell-mediated immunity and function in activating macrophages

TH2 cells produce IL-4, IL-5, and IL-10 and are important for humoral immunity

Mast cellKey features Fried-egg appearance with central round

nucleus and surrounding oval, bluish cytoplasm Contain metachromatic granules composed of

heparin, histamine, tryptase, carboxypeptidase, leukotrienes

Important in immediate-type hypersensitivity reactions

NeutrophilKey features Predominant cell in acute infection

Multilobulated nucleus

EosinophilKey features IL-5 induces eosinophil production

Bilobed nucleus with granular cytoplasm containing major basic protein, eosinophil cationic protein, catalase, and other proteins

Plasma cellKey features Eccentric nucleus with clock face Perinuclear pale space corresponding to rough

endoplasmic reticulum (described by Hopf) Pink cytoplasm

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Figure 1-58 Mastocytoma

Figure 1-60 Eosinophils in dermal hypersensitivity response

Figure 1-59 Neutrophils in Sweets syndrome