Page 468 - Veterinary Immunology, 10th Edition

cyclophosphamide or thalidomide may be employed. In humans,
VetBooks.ir major improvements in survival have resulted from the use of

monoclonal antibodies against B cell antigens.
Sometimes, in clinically normal humans, dogs, and horses, a

monoclonal gammopathy may develop that is not due to a
myeloma. These monoclonal antibodies are usually an accidental
finding on serum electrophoresis, and their origin is unclear. They
may disappear spontaneously within a short period, or they may

persist for many years. Affected animals may show abnormally
large numbers of plasma cells in their internal organs on necropsy.

Polyclonal Gammopathies

In contrast to monoclonal gammopathies, which are usually

produced by a myeloma, polyclonal gammopathies are observed in
many different diseases. Polyclonal gammopathies are
characterized by an increase in all immunoglobulins as a result of

excessive activity of many different clones of plasma cells. The
condition that most resembles a myeloma is Aleutian disease in
mink (Chapter 27). Animals infected by the Aleutian disease
parvovirus show marked plasmacytosis and lymphocyte infiltration
of many organs and tissues, as well as polyclonal (occasionally

monoclonal) gammopathy. As a result of the elevated
immunoglobulin levels, affected mink experience a hyperviscosity
syndrome and are severely immunosuppressed.

Other causes of polyclonal gammopathy include autoimmune
diseases such as systemic lupus erythematosus, rheumatoid
arthritis, and myasthenia gravis (Chapter 38), as well as infections
such as tropical pancytopenia of dogs due to Ehrlichia canis, African
trypanosomiasis, and chronic bacterial infections such as pyometra

and pyoderma. In horses heavily parasitized with Strongylus
vulgaris, polyclonal IgG3 levels rise significantly. Polyclonal
gammopathy also occurs in virus diseases such as feline infectious

peritonitis and African swine fever, and in diseases in which there
is extensive liver damage.

468