Immunokinetics of a single dose of thymopoietin pentapeptide.

14 patients with classical or definite rheumatoid arthritis and a low number of E-rosette forming cells were given single doses of 5 mg and 50 mg of thymopoietin intravenously. Thymopoietin pentapeptide produced a dose-related sustained increase in E-rosette forming lymphocytes as shown by the decrease of thymopoietin dependent rosetting ratio. A single dose of 50 mg restored the number of E-rosette forming cells to normal after 12 h and this effect lasted 60 to 7 days. With the administration of 5 E-rosette forming cells markedly increased after 12 h and returned to the pretreatment level on the 2nd day. These immunokinetic data clarify some aspects of the clinical pharmacology of thymopoietin pentapeptide and must be considered for a rational schedule of treatment with the drug.