Biology of Disease

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Figure 4.18 Photomicrograph showing the detection of cytoplasmic

antigens following the production of a colored marker using enzyme

immunohistochemistry.

Figure 4.17 (A) Schematic showing the detection of cellular antigens, in this case CD3, by immunofluorescence as described in the text. (B) Computer

generated image showing the distribution of membrane antigens as detected by immunofluorescence.

CD3

Mouse antiCD3

A)

Fluorescein-

conjugated

antimouse IgG

Represents the

fluorochrome,

fluorescein

B)

Protein Rolein vivo Found on

Surface immunoglobulin epitope receptor B lymphocytes

CD3 signal transduction following

binding of T cell

receptor to epitope

all mature T lymphocytes

CD4 coreceptor molecule helper T lymphocytes (TH)

CD8 coreceptor molecule cytotoxic T cell precursors (TC) and

cytotoxic T lymphocytes (CTL)

Table 4.4Marker proteins for T and B lymphocytes

Labels other than fluorochromes are available, which

allow the production of permanent preparations

and the use of an ordinary light microscope. For

example, antibodies labeled with an enzyme, such

as horseradish peroxidase or alkaline phosphatase

can be located by their ability to convert a colorless

substrate into an insoluble colored compound

that can be seen when the cells are examined

microscopically. This technique is called enzyme

immunohistochemistry (Figure 4.18).

BOX 4.3 Distinguishing T and B lymphocytes