Androstanediol glucuronide (Adiol G) has been reported to be a marker of peripheral androgen metabolism and action. It consists of two isomers, Adiol 3-G and Adiol 17-G. Adiol G is formed from unconjugated precursors by the enzyme glucuronyl transferase.

A delta-4 C19 steroid that is produced not only in the testis, but also in the ovary and the adrenal cortex. Depending on the tissue type, androstenedione can serve as a precursor to testosterone as well as estrone and estradiol.

It is thus a steroidal hormone produced in male and female gonads, as well as in the adrenal glands, and it is known for its key role in the production of estrogen and testosterone.

Angiotensin is a peptide endocrine hormone and an important part of the renin-angiotensin-aldosterone system, an inter-related endocrine system important in volume and blood pressure control. Angiotensinogen, an alpha-globulin, and the peptide prohormone is synthesized primarily by the liver and circulates in plasma.

Anti-phosphatidylserine prothrombin antibodies (aPSPT) are reported to be highly associated with the lupus anticoagulant (LAC) in established antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) cohorts.

Anti-phosphatidylserine prothrombin antibodies (aPSPT) are reported to be highly associated with the lupus anticoagulant (LAC) in established antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) cohorts.

Systemic lupus erythematosus (SLE) is characterized by high-titer serological autoantibodies, including antibodies that bind to double-stranded DNA (dsDNA). The origin, specificity, and pathogenicity of anti-dsDNA antibodies have been studied from a wider perspective. These autoantibodies have been suggested to contribute to multiple end-organ injuries, especially to lupus nephritis, in patients with SLE.

Antibodies directed against myeloperoxidase (anti-MPO) are used in the diagnostic and follow-up of ANCA-associated vasculitis (AAV), along anti-PR3.

Anti-citrullinated peptide (or anti-CCP) antibodies are an essential immunological marker in the diagnosis of rheumatoid arthritis (RA) and are among the poor prognosis factors.

Complement component 1q (C1q) is a soluble protein complex acting as a key bridge between innate and adaptive immune responses. During infection and tissue damage, C1q binds to the fragment crystallizable (Fc) region of circulating IgG or IgM antibodies, apoptotic cells, bacterial surfaces, and ligand-bound C-reactive protein. This allows for the aggregation of antigen–antibody–C1q complexes to form. This process, known as opsonization, allows for increased phagocytic efficiency of cells such as macrophages via the classic complement cascade, which ends with the formation of a membrane attack complex that initiates target cell lysis.

Antibodies to liver cytosol antigen type 1 (anti-LC1), which recognize a 60-kd peptide contained in the liver cytosolic fraction, have been reported to define a subset of autoimmune hepatitis (AIH) either negative for other autoantibodies or positive for anti-liver kidney microsomal antibody type 1 (LKM-1) and to be best detected in immunodiffusion.