Final answer:
The factor present in the blood for clients with rheumatoid arthritis is cytokines, which are involved in the inflammatory process associated with the disease.
Step-by-step explanation:
The factor present in the blood when a client has rheumatoid arthritis (RA) is cytokines. RA is characterized by type III hypersensitivity reactions, which involve the chronic release of inflammatory cytokines such as IL-1, IL-6, and tumor necrosis factor-alpha (TNF-α). These cytokines play a critical role in the joint inflammation and immune response that define RA. Additionally, RA patients often have elevated levels of rheumatoid factor (RF) antibodies and anticyclic citrullinated peptide antibodies (anti-CCP). Diagnosis of RA may involve testing for these factors, as well as evaluating C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR).