1. Evaluate the levels of serum (sPD1) in RA patients with ILD and those without.
2. Detect subclinical RA-ILD for early diagnosis and management of this devastating manifestation of RA

Rheumatoid arthritis is a chronic autoimmune disease that is characterized by a systemic inflammatory state that affects joints and other organs .

There are many types of RA-related pulmonary diseases. RA-related pulmonary diseases include airway disease such as bronchiolitis. There are interstitial lung diseases that include non-specific interstitial pneumonitis and usual interstitial pneumonia .

The pathogenesis of RA is multifactorial with contributions from genetic and environmental factors. (CD4+) T-cells is responsible for pro-inflammatory cytokines production and subsequent joint destruction .

The aetiology of RA-ILD may be related to smoking and other factors that activate autoimmunity and the attack of post-transcriptionally modified self-proteins, such as citrullinated peptides. Citrullinated peptide can be produced in the lungs of some patients, causing a pulmonary fibrosis .

Major subtypes of RA-ILD are defined by their histopathological or (HRCT) patterns

. Programmed death-1 belongs to CD28/B7 family and is expressed on the surface of activated T cells, B cells, NK cells, dendritic cells and Treg cells. sPD-1 is the soluble form of PD-1 that is obtained by phosphoric acid hydrolysis of membrane type PD-1 .

Programmed death-1 and its ligands are important negative regulators of the immune system. .

In RA, Persistent synovial T cell activation and inflammation may be reasoned to positive regulators overexpression, aberrant expression of negative regulators or functional antagonism of these molecules by soluble factors .

sPD-1 inhibits the PD-1/PD-L signalling pathway by interacting with PD-Ls and promotes the T cell activation .

Inclusion Criteria:

• Adult RA Patients who fulfilled the 2010 ACR/European league against rheumatism (EULAR) criteria for the classification of RA (7).
• Adult RA patients with ILD (Nonspecific idiopathic interstitial pneumonia more than 16 years old).

Exclusion Criteria:

• Patients with other autoimmune diseases (systemic lupus erythematosus, polyarteritis nodosa sarcoidosis, dermatomyositis, scleroderma, spondylarthritis and inflammatory bowel disease).
• RA patients with lung affection other than ILD
• Patients with malignant tumors
• Patients with active infection
• Patients with severe heart, lung, and kidney dysfunction
• Patients with tuberculosis, pulmonary infection, chronic obstructive pulmonary disease, bronchiectasis, lung tumor, and pneumoconiosis disease.
• Uses of drugs (other than RA medication) known to cause ILD such as antimicrobial agents (Sulphonamide), cardiovascular agents (amiodarone) and Bromocriptine.

1. Adult RA Patients
2. Adult RA patients with ILD
3. Adult healthy control