Br J Ophthalmol 1999;83:973-979
( August )
Suppression of induction of experimental immune mediated
blepharoconjunctivitis by tolerogenic conjugates of the antigen and
monomethoxypolyethylene glycol
Atsuki Fukushimaa, Koji Nishinoa, Hironori Yoshidaa, Masaru Takatab, Hisayuki Uenoa
a Department of
Ophthalmology, Kochi Medical School, Nankoku City, Japan, b Department of Immunology, Kochi Medical School,
Nankoku City, Japan
Correspondence to: Atsuki Fukushima, Laboratory of Immunology, Department of
Ophthalmology, Kochi Medical School, Kohasu, Oko-cho, Nankoku
783-8505, Japan.
Accepted for publication 15 March 1999
AIM
Covalent
conjugates consisting of diverse antigens coupled to optimal numbers of
monomethoxypolyethylene glycol (mPEG) molecules have been shown to
suppress antigen specific antibody formation. In this study, the
possibility was examined that the same conjugates might prevent
experimental immune mediated blepharoconjunctivitis (EC, formerly EAC)
which had been shown to be caused by CD4+ T cells
that is,
to cell mediated immunity.
METHODS
6-8 week old
male Lewis rats were used. The test groups of rats received two
intravenous injections, each of 300 µg, of a conjugate of ovalbumin
mPEG (OVA(mPEG)11) in phosphate buffered saline (PBS), 14 and 28 days before the single immunisation with OVA in complete
Freund's adjuvant. The rats were challenged 3 weeks later by eye drops
containing OVA; 24 hours later they were sacrificed, and their eyes,
blood, and lymph nodes were harvested for histological examination and
determination of anti-OVA antibody titres and levels of cellular
immunity. Two control groups received PBS or OVA in PBS before
immunisation. Furthermore, the possibility that OVA(mPEG)11
may have induced OVA specific suppressor cells was tested by
establishing the effects of the co-transfer of splenocytes from
OVA(mPEG)11 treated rats with OVA primed lymph node cells on the manifestations of EC.
RESULTS
Either PBS or
OVA pretreated rats, which had not received OVA(mPEG)11,
developed high levels of antibodies and cell mediated immune responses
to OVA, and application of eye drops led to blepharoconjunctivitis with
massive cellular infiltration. In contrast, pretreatment with
OVA(mPEG)11 prevented cellular infiltration into the lids and conjunctivas, as well as the formation of detectable humoral and
cellular immunity against OVA. Co-transfer of splenocytes from
OVA(mPEG)11 treated rats with OVA primed lymph node cells suppressed the cellular infiltration on application of OVA on the conjunctiva.
CONCLUSIONS
These data
indicate that intravenous injection of OVA(mPEG)11
conjugates suppressed both humoral and cellular immunity by the effects
of antigen specific suppressor cells, thus leading to the inhibition of
development of EC.
© 1999 by British Journal of Ophthalmology