I started taking prednisone nearly 6 years ago for my rheumatological issues, the PMR, and mild RA, when I was diagnosed with Inststicial Lung Disease 5 years ago, the pulmonologist would have added prednisone. but I was already on it. I have been taking 5mg to 10mg as the need arises, we tried to lower the dosage to 2mg, but things did flare up, so I would say it must be helping. The Rheumatologist would like to add a biological like Certolizumab (taking me off Hydroxychloroquine) but he is concerned about as he puts it "rocking the boat".
I don't do well with many medications and every time we try to add something new I end up having issues. Hydroxychloroquine is not considered an immunosuppressant but it is the closest that I have been able to take without developing other health issues. So the short answer is YES. I think things would be much worse without the prednisone.