Background: Syndecan-1, a heparan sulfate proteoglycan present on the membr
ane of keratinocytes, functions in intercellular adhesion. Acantholysis and
spongiosis are both characterized by diminished intercellular adhesion tha
t may lead to blister formation. In spongiotic conditions, desmosomal stret
ching occurs prior to cell separation while in acantholytic conditions, cel
l separation occurs without stretching. While many of the structural relati
onships have been described, the molecular interactions regulating keratino
cyte to keratinocyte adhesion are not yet fully understood.
Methods: Sections from ten cases of Grover's disease, two pemphigus vulgari
s, one pemphigus foliaceus, one bullous pemphigoid, two herpes simplex, and
ten spongiotic dermatitis were stained with BB-4, a monoclonal anti-syndec
an-1 antibody.
Results: Nine of ten Grover's, all three pemphigus, and both herpes cases s
howed absent or markedly decreased syndecan-1 expression by acantholytic ke
ratinocytes, with a sharp delineation from adjacent unaffected skin. The re
maining Grover's case showed moderate loss of syndecan-1 expression. Te pem
phigus foliaceus case showed retention of staining along the basal cell lay
er, but expression was lost in the mid stratum spinosum. All ten spongiotic
cases showed a diffuse mild decrease in staining, with loss of syndecan-1
expression surrounding microvesicles. Bullous pemphigoid, as expected, did
not show loss of syndecan expression.
Conclusions: The loss of syndecan-1 expression evident in acantholytic cond
itions and, to a lesser extent in spongiotic conditions, may contribute to
the decreased intercellular adhesion characteristic of these lesions.