We want to correct some statements that we published in an
earlier volume of
IOVS.
1 We described microglia
and macrophages in the normal rat retina and the response of these
cells during the endotoxin-induced uveitis model (EIU). Retinal
wholemounts from normal rats and at various time points after endotoxin
injection were stained with the monoclonal antibodies ED1 and ED2. We
reported the staining pattern and densities (196–271
cells/mm
2 ) of these two antibodies to be
essentially similar and described a massive influx of macrophages 24 to
96 hours after endotoxin injection. We reported that these cells were
both ED1+ and ED2+. Since then we have repeated the experiments and
performed similar protocols in collaboration with Dr. Paul McMenamin,
who has extensive experience with these monoclonal antibodies, during a
sabbatical visit he paid to our Institute. We experienced some
difficulties in the staining of ED2, which caused us to review the
material originally published in
IOVS. With the aid of Dr.
McMenamin, we performed extensive tests with the monoclonal antibody
batches used in the original experiments, compared them with new
batches, and concluded that retinal microglia, i.e., the macrophages
within the retinal parenchyma, are weakly ED1+ but ED2−. The original
findings that these cells were ED2+ was in fact erroneous and appeared
to be due to an error in labeling of antibodies at the time of
aliquoting. It is important that this issue be clarified, because a
number of studies of normal rat retinal tissue have failed to find
significant numbers of ED2+ macrophages in the retina.
2 3 Furthermore, no influx of ED2+ macrophages was noted in EIU by Pouvreau
et al.
2 We apologize for any inconvenience caused to our
colleagues as a result of this error.