Autoantibodies and Autoimmunity
469
Fig. 3
Immunofluorescence patterns
produced by autoantibodies recognizing
structural and functional domains
within the cell nucleus (magniFcation,
350
×
). (a) Antinuclear lamin B1
antibodies identify the periphery of the
nucleus; arrowheads show the
re-formation of the nuclear envelope
during late telophase. (b) Anti-Sm
antibodies localize the U1, U2, and
U4–U6 snRNP particles as a speckled
nuclear pattern. (c) Anti-PCNA
antibodies recognize the auxiliary
protein of DNA polymerase delta during
active DNA synthesis, producing
different fluorescence patterns as cells
progress through mitosis. (d) Anti-p80
coilin antibodies highlight subnuclear
domains known as Cajal bodies, which
disappear during metaphase
(arrowhead). (e) AntiFbrillarin
antibodies target the nucleolus and
produce a characteristic clumpy pattern
in interphase cells, decorating the
chromosomes from late metaphase
until cell division (arrowhead).
(f) Antibodies to centromeric proteins
A, B, and C produce a discrete speckling
of the interphase nucleus and identify
the centromeric region of the dividing
chromosomes during cell division
(arrowheads).
(a)
(b)
(c)
(d)
(e)
(f)
are labeled with a different chromophore
and by comparing the fluorescence pat-
terns. Immunolocalization of the non-
snRNP spliceosome component SC-35 was
achieved in this way by comparison of anti-
SC-35 antisera with the IIF pattern of au-
toimmune anti-Sm sera, which recognize
protein components of the spliceosome.
One feature of autoantibodies that dis-
tinguishes them from antibodies raised by
speci±c immunization, and underscores
their uniqueness, is their ability to recog-
nize their target antigen not only from the
host but also from a variety of species.
The extent of this species cross-reactivity
is dependent on the evolutionary conser-
vation of the autoantigen and is related
to the conservation of protein sequence.
Oneexamp
leisthesnoRNPp
ro
te
in±b
-
rillarin. Using autoantibodies in a variety
of immunological techniques, including
IIF, this protein can be recognized from
species as diverse as humans and the
unicellular yeast
Saccharomyces cerevisiae
.
cDNA cloning of ±brillarin has con±rmed
the expected high degree of conservation
of the protein sequence.
The reactivity of autoantibodies with
conserved sequence and conformational
protein elements has made them useful
reagents in the cloning of cDNAs of
expressed proteins from cDNA libraries
from
a
variety
of
species.
However,
because of their reactivity with the human
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