Microbiology and Immunology

Laboratory techniques in immunology WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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done using a plastic plate containing many small wells. This

allows up to 100 samples to be tested in a single experiment.

ELISA can reveal the presence of antigen in fluids such as a

patient’s serum, for example.

The nature of the antibody can be important in labora-

tory immunological techniques. Antibodies such as those

raised in a rabbit or a goat are described as being polyclonal

in nature. That is, they do recognize a certain antigenic

region. But if that region is present on different molecules,

the antibody will react with all the molecules. The process of

monoclonal antibody production can make antigenic identifi-

cation much more specific, and has revolutionized immuno-

logical analysis.

Monoclonal antibodies are targeted against a single

antigenic site. Furthermore, large amounts of the antibody can

be made. This is achieved by fusing the antibody-producing

cell obtained from an immunized mouse with a tumor cell.

The resulting hybrid is known as a hybridoma. A particular

hybridoma will mass-produce the antibody and will express

the antibody on the surface of the cell. Because hybridoma

cells are immortal, they grow and divide indefinitely. Hence

the production of antibody can be ceaseless.

Monoclonal antibodies are very useful in a clinical

immunology laboratory, as an aid to diagnose diseases and to

detect the presence of foreign or abnormal components in the

blood. In the research immunology laboratory, monoclonal

technology enables the specific detection of an antigenic tar-

get and makes possible the development of highly specific

vaccines.

One example of the utility of monoclonal antibodies in

an immunology laboratory is their use in the technique of flow

cytometry. This technique separates sample as individual sam-

ple molecules pass by a detector. Sample can be treated with

monoclonal antibody followed by a second treatment with an

antibody to the monoclonal to which is attached a molecule

that will fluoresce when exposed to a certain wavelength of

light. When the labeled sample passes by the detector and is

illuminated (typically by laser light of the pre-determined

wavelength), the labeled sample molecules will fluoresce.

These can be detected and will be shunted off to a special col-

lection receptacle. Many sorts of analyses are possible using

flow cytometry, from the distinguishing of one type of bacte-

ria from another to the level of the genetic material compris-

ing such samples.

See alsoAntibody-antigen, biochemical and molecular reac-

tions

Titration burettes are used to carefully control the pH of solutions used in laboratory procedures.

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