Is sero negative autoimmune/inflammatory disease real? i was told this by 1 a neurologist but the rheumatologist just sniggered when i told him

Spondyloarthropathy: Seronegative spondyloarthropathy is a form of arthritis that does not have the typical rheumatoid factor antibodies. There are other inflammatory diseases, mostly immune system disorders, that do not have autoantibodies and are thus seronegative. Typically, autoimmune diseases are characterized by autoantibody formation and thus would not be seronegative.