Right, claims 21 thru 24 are all independent claims without attached dependent claims anyway.
For example, because claim 17 ( A use according to claim 15 wherein said inflammatory disease is psoriasis.) refers to claim 15, claim 17 is a 'dependent claim', relying on the validity of claim 15. And claim 15 is also a dependent claim relying on one of claims 1-4 to be valid. If claims 1-4 were all not novel, then claim 15 and claim 17 would both cease to be novel as well.
There are no claims dependent upon claim 23 - so get it outta there!!! hehe
and... we're good.
That's how I read it anyways.