Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

V. Immunohistochemistry/Immunocytochemistry
759
The immunophenotyping of canine lymphoma has
received considerable attention as a potential prognostic indicator.
Several studies suggest that dogs with B cell lymphoma
may have longer survival than those with T cell lymphoma
(Dobson et al. , 2001 ; Kiupel et al. , 1999 ; Ponce et al. , 2004 ;
Teske et al. , 1994 ). It is unclear if immunophenotype is an
important prognostic factor in feline lymphoma ( Patterson-
Kane et al. , 2004 ).
Different anatomic forms of lymphoma have also been
associated with specific cell types of origin. For example, in
the dog, cutaneous lymphoma is primarily of T cell origin,
and epitheliotrophic lymphoma is exclusively of T cell origin
( Day, 1995 ). There also appears to be breed differences in lymphoma.
In one study, 82% of boxer dogs had T cell lymphoma,
whereas other only 50% of the golden retrievers and rottweilers
studied had T cell lymphoma ( Lurie et al. , 2004 ). In cats,
mediastinal and intestinal lymphoma appear to be predominantly
T cell in origin ( Gabor et al. , 1999 ; Zwahlen et al. , 1998 );
however, there may be some worldwide geographic differences
in the distribution of B cell lymphomas among cats.
Similar immunophenotyping techniques have been
successfully applied to fine needle aspirate samples of
lymph nodes using flow cytometry ( Gibson et al. , 2004 )
and cytospin cytology preparations ( Caniatti et al. , 1996 ).
Immunophenotyping of leukocyte tumors has also been
applied in other species including the horse ( Kelley and
Mahaffey, 1998 ), cow ( Vernau et al. , 1997 ), and ferret
( Coleman et al. , 1998 ).
F. Other Markers
1 . Von Willebrand’s Factor (Factor VIII-Related Antigen)
Von Willebrand’s factor, part of the factor VIII complex, is
restricted to endothelial cells, megakaryocytes, and platelets.
Positive immunoreactivity to factor VIII-related antigen
is useful in diagnosing vascular neoplasia in a variety
of species. Factor VIII-related antigen has also been used
to identify tumor microvessels, and various determinations
of microvessel density may carry prognostic significance.
In one study of malignant canine mammary tumors, a high
tumor vascular density was associated with an increased
likelihood of local tumor recurrence (Griffey et al. , 1998) .
Intratumoral vascular density has also been shown to predict
survival in dogs with mast cell tumors ( Preziosi et al. ,
2004 ).
2 . Actin Microfi laments
Vertebrates have at least six tissue-specific forms of actin.
There are actins specific for skeletal muscle, cardiac muscle,
vascular smooth muscle, and enteric smooth muscle.
Alpha-smooth muscle actin may be a useful marker to distinguish
canine hemangiopericytomas from other peripheral
nerve sheath tumors (Chijiwa et al. , 2004) .
3 . Skeletal Myosin
Antibodies that distinguish between smooth muscle and
sarcomeric myosin found in skeletal and cardiac muscle
may be helpful in determining the cell of origin for muscle
tumors.
4 . S-100 Proteins
S-100 was originally isolated from brain and thought
to be specific for glial cells; however, S-100 proteins
have subsequently been identified in a variety of nonneuroectodermal
tissues. In dogs, S-100 immunoreactivity
has been identified in melanoma and amelanotic melanoma,
gastrointestinal stromal tumors, and schwannomas, making
it nonspecific for melanoma (Choi and Kusewitt, 2003) .
Because the diagnosis of canine melanoma is often challenging,
having positive immunoreactivity for S-100,
vimentin, and neuron-specific enolase and negative immunoreactivity
for cytokeratins supports a tentative diagnosis
of melanoma. However, other immunohistochemical markers,
such as tyrosinase-related protein-2 (TRP-2), have
apparently greater specificity for melanocytic tumors and
may be more useful than S-100 (Choi and Kusewitt, 2003) .
5 . Neuron-Specifi c Enolase
Neuron-specific enolase (NSE) is the γ -subunit of the
enolase enzyme involved in the glycolytic pathway and
is characteristic of neural cells. Several tumors have been
shown to be immunoreactive with NSE including medullary
thyroid (C-cell) tumors, chordomas, and ganglioneuroblastomas.
Meningiomas and melanomas may also have
positive immunoreactivity with NSE (Barnhart et al. , 2002 ;
Koenig et al. , 2001) .
6 . Chromogranin A
The diagnosis of cancers arising from neuroendocrine
cells, those with neurotransmitter, neuromodulator, or neuropeptide
hormone production; dense-core secretory granules;
and the absence of axons and synapses, is aided by
the use of neuroendocrine markers, particularly chromogranin
A (Barakat et al. , 2004) . Chromogranin A is present
in the secretory granules of endocrine cells and has been a
useful immunohistochemical marker for diagnosing a variety
of neuroendocrine tumors of animals, including carcinoid,
pheochromocytoma, insulinoma, and neuroendocrine
carcinoma (Barthez et al. , 1997 ; Doss et al. , 1998 ; Morrell
et al. , 2002 ; Myers et al. , 1997 ; Sako et al. , 2003, 2005) .
7 . Type IV Collagen and Laminin
Type IV collagen and laminin make up basement membranes
and can be visualized with light microscopy through