Description

Jo-1 antibody, also known as anti-Jo-1 antibody or anti-histidyl-tRNA synthetase antibody, is a type of autoantibody found in the blood of some individuals with certain autoimmune diseases, particularly inflammatory myopathies such as polymyositis and dermatomyositis.

Histidyl-tRNA synthetase is an enzyme involved in protein synthesis. In autoimmune diseases like polymyositis and dermatomyositis, the body’s immune system mistakenly targets its own tissues, including muscle cells, leading to inflammation and damage. Anti-Jo-1 antibodies specifically target histidyl-tRNA synthetase.

The presence of Jo-1 antibodies in the blood can help in the diagnosis of polymyositis or dermatomyositis, especially when combined with clinical symptoms such as muscle weakness, skin rash, and elevated muscle enzyme levels (e.g., creatine kinase). However, not all individuals with these conditions will test positive for Jo-1 antibodies, and conversely, some individuals without these diseases may have positive Jo-1 antibody tests. Therefore, diagnosis is based on a combination of clinical findings, laboratory tests, and sometimes muscle biopsies.