Tolerance and cerebrospinal fluid pharmacokinetics of intrathecally administered human natural interleukin-2: a phase I trial.

Recombinant interleukin-2 (rIL-2) is at present widely applied in the immunotherapy of various advanced cancers. As a number of side effects following the administration of rIL-2, either alone or in combination with lymphokine-activated killer (LAK-) cells, have been reported, a preparation of human leukocyte-derived and fully glycosylated interleukin-2 was used in the present study. We have recently demonstrated in cats that this natural IL-2 (nIL-2) is well tolerated and that the distribution and elimination half-lifes following intrathecal (i.th.) application are considerably longer than those after intravenous (i.v.) injection. To determine whether these long half-lifes and the good tolerance of i.th. given nIL-2 are also found in man, four patients with meningeosis neoplastica received repeated injections of human nIL-2 i.th.. Cerebrospinal fluid samples were drawn at different time intervals from either the lateral ventricle or lumbar subarachnoid space. The doses of nIL-2 ranged from 2 x 10(4) to 4 x 10(5) IU per injection. Only minor side effects were noted in one patient. The half-lifes for distribution and elimination of i.th. given nIL-2 ranged between 0.5-1.7 hours and 4.9-14.4 hours respectively. A linear relationship exists between the i.th. dose of nIL-2 and the area under the cerebrospinal fluid activity time profile curve.

Interleukin-2 and blood brain barrier in cats: pharmacokinetics and tolerance following intrathecal and intravenous administration.

Single bolus doses of glycosylated human interleukin-2 (n IL-2) in the range of 2.8 x 10(3) to 2.0 x 10(6) IU/kg were administered to anesthesized cats via the cephalic vein (n = 10) or using suboccipital puncture (n = 8). CSF (cerebrospinal fluid) and blood samples were collected by repeated puncture. The n IL-2 concentration in four cats was determined on the basis of its biologic activity using 3H-thymidine incorporation into human ConA-blasts and by radioimmunoassay. In additional experiments radioactivity was determined in cerebrospinal fluid and serum after intravenous and intrathecal (i.th.) application of 5.8 x 10(3) - 3.2 x 10(3) IU/kg of 14C-acetyl-n IL-2 in regular time intervals. CSF and serum concentration time-profiles show a biexponential decline in the plasma elimination phase with half-lives of 4 min (alpha-phase) and 90 min (beta-phase) after intravenous and 20-120 min (alpha-phase) and 2-16 hours (beta-phase) after intrathecal application. There is a trend towards longer terminal elimination half-lives with increasing doses. Interleukin-2 is able to penetrate the blood brain barrier from the circulation into the cerebrospinal fluid and vice versa. Due to a slow rate of penetration and rapid elimination from blood only traces of n IL-2 (2-8 IU/ml) are detected in CSF after i.v. injection of 2 x 10(6) IU/kg, whereas concentrations between 400 and 1600 IU/ml are maintained in CSF for several hours following i.th. administration of 2-10 x 10(5) IU/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian rhythm of soluble interleukin-2 receptor in healthy individuals.

The cytokine levels of soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6) and tumor-necrosis-factor alpha (TNF-alpha) were studied in 12 healthy volunteers at 11 different times of day. TNF-alpha levels were below the detection limit, and IL-6 levels were at baseline values of the respective assay used. Interindividual variations were found for the plasma levels of sIL-2R (179-524 U/ml). Shedded IL-2 receptors displayed a pronounced circadian phase-dependency (p less than 0.0001) with a peak value at 12:29 h and a trough at 4:14 h when a complex cosine function (period lengths: 24 h plus 12 h) was fitted to the data. These findings may be of importance when using sIL-2R as a diagnostic tool as well as in controlling efficacy of drug treatment.

Artificial dimers of native actin: preparation and properties in biological functions.

With the aid of tartryl-bis-epsilon-aminocaprylazide artificial dimers were produced from F actin from rabbit striated muscle. These derivatives will not polymerize by themselves but are able to copolymerize fully with native G actin. By modification of a single side chain per dimer, this copolymerization was completely inhibited. The dimers are able to activate subfragment 1 ATPase of myosin and bind to DNase I with inactivation of the enzyme in the same manner as native G actin. Within the dimer, one ADP is immobilized and will exchange against ATP extremely slowly. The dimers do not bind to the mushroom toxin phalloidin.