Test Directory

Histones are lysine-rich and arginine-rich basic proteins of eukaryotic cells which are predominantly found as complexes with DNA. Antibodies to histones are detected in approximately 30% to 60% of patients with systemic lupus erythematosus (SLE), but their presence in about 95% of patients with drug-induced lupus is more important diagnostically. Drug-induced lupus (primarily caused by procainamide and hydralazine) is clinically similar to SLE, except that the former patients do not have kidney or central nervous system involvement and they do not demonstrate the multiple types of antinuclear antibodies (ANAs) often found in SLE patients. In addition, drug-induced antihistone antibodies react strongly with H2a/H2b fragments (in procainamide-induced SLE) as well as H3 and H4 (in hydralazine-induced SLE). In patients with drug-induced lupus, antihistone antibodies are usually the only ANAs, although antibodies to denaturated DNA have been detected in a small percentage of patients. Antihistone antibodies also occur in approximately 20% of patients with rheumatoid arthritis.

Specimen Type: Serum

Collection Container: Gold Top, Serum Separator or Red Top, Plain

Desired Specimen Volume: 1 mL

1. Collect gold top, serum separator tube or red top, plain tube via venipuncture.

1. Separate serum from cells.
2. Transfer 1 mL of serum to a clear aliquot tube.

Transport to the laboratory refrigerated. 

• Hemolysis
• Icterus
• Lipemia
• Bacterial contamination

• Negative: <1.0 units

• Weak positive: 1.0−1.5 units

• Moderate positive: 1.6−2.5 units

• Strong positive: >2.5 units

The expected value in the normal population is negative; however, apparently healthy individuals may contain ANA in their sera. This percentage increases with aging, particularly in the seventh decade of life. Certain therapeutic drug regimens and viral syndromes may also cause ANAs.

• DIL
• Drug-induced Lupus Antibodies
• H2a/H2b and H3 and H4 Antibodies
• Histone Antibodies