Refusal to accept autism

My 18yr old son was diagnosed with high functioning autism when he was 11yrs old. He is now asking us to find him a cure for his autism and gets cross when he tells his friends how he feels and finds them unable to understand why he hates being autistic. Today he asked us to get him a second opinion as he is refusing to acknowledge that he is autistic now. He is currently having counselling for a separate issue that he has been on a waiting list for for a while and he has been calmer since starting counselling. His meltdowns have also lessened but this denial seems to have replaced that. I am just wondering if anyone has been through a similar issue, either themselves or with a child? If so any advice with how to handle this?

Thanks