T. Takao et al., SPECIES-DIFFERENCES IN [I-125] INTERLEUKIN-1 BINDING IN BRAIN, ENDOCRINE AND IMMUNE TISSUES, Brain research, 623(1), 1993, pp. 172-176
There were dramatic species differences in the level of [I-125]recombi
nant human interleukin-1alpha ([I-125]hlL-1alpha) binding with high le
vels of binding present in mouse and rabbit tissues, while no specific
binding was present in rat and guinea pig tissues. Utilizing [I-125]h
IL-1alpha moderate to high levels of specific binding were observed in
EL-4 6.1 cells (representative of Type I IL-1 receptors) and in mouse
hippocampus, spleen and testis; however, no specific [I-125]hIL-1alph
a binding was present in Raji cells (representative of Type II IL-1 re
ceptors) and in rat tissues. On the other hand, utilizing [I-125]hIL-l
P, high specific IL-1 binding was present in EL-4 6.1 and Raji cells a
nd moderate binding was evident in mouse tissues, whereas specific [I-
125]hIL-1beta binding to rat tissues was not detectable. Moreover, no
IL-1 binding in rat tissues was observed using [I-125]hIL-1 receptor a
ntagonist, (I-125]mouse IL-1beta or the homologous radioligands [I-125
]rat IL-1beta or [I-125]rat IL-1 receptor antagonist. These data demon
strate that under optimal conditions for labeling Type I or Type II IL
-1 receptors, no specific binding is observed in rat tissues suggestin
g the presence of novel IL-1 receptor(s) in rat tissues.