ANTI-HISTONE ANTIBODIES

CLINICAL UTILITY:

Histones are basic nuclear proteins which are bound to DNA and form an integral part of the chromatin structure. Antibodies to histones occur in the sera of approximately 90% of patients with drug-induced SLE. Patients with naturally-occurring (idiopathic) SLE sometimes have anti-histone antibodies, but in addition have a variety of other anti-nuclear antibodies in their sera. Rheumatoid arthritis patients also occasionally develop anti-histone antibodies as well as other ANA. In contrast, drug-induced SLE is marked by the appearance of mainly anti-histone antibodies. Drugs which are implicated in the formation of drug-induced ANAs include procainamide, hydralazine, phenothiazines, phenytoin, carbamazepine, alpha methyl dopa, isoniazid and d-penicillamine.

METHOD DESCRIPTION:

Indirect immunofluorescence is used to detect anti-histone antibodies. The procedure involves preparation of three types of liver tissue sections on slides: in the first type, the nucleus (with histones) is intact; in the second, the histones and soluble nuclear molecules are extracted with 0.1 M HCl, leaving the DNA in the nucleus; in the third, the previously extracted slides are incubated with a solution of purified calf thymus histone to reconstitute the DNA-histone complex. Anti-histone antibodies will fluoresce on the intact and histone-reconstituted sections, but be negative on the acid-extracted section. Results are reported as positive or negative for anti-histone antibody. An ANA must be positive in order to perform the test for antibodies to histones.

REFERENCE RANGE:

Negative.

SPECIMEN REQUIREMENTS:

0.5 ml serum. Freeze.