Although gamma interferon (gamma-IFN) may be involved in the pathogenesis of exacerbations of multiple sclerosis (MS), whether it plays a role in chronic progressive MS is not known. To investigate this, we retrospectively analyzed serum samples from nine chronic progressive MS patients who were treated with monthly intravenous infusions of the interferon inducer polyinosinic acid polycytidylic acid polylysine in carboxymethylcellulose (poly ICLC). Using a bioassay we found that the mean peak total interferon level was 177 U/ml 12 hours after infusion, and using a radioimmunoassay we found that the mean peak gamma-IFN level was 15.9 U/ml 12 hours after infusion, so that gamma-IFN made up approximately 10% of the total. Greater gamma-IFN induction did not correlate with clinical worsening; induced gamma-IFN levels were not higher in two patients who worsened on treatment, and the highest levels were found in a patient who remained stable. Either chronic progressive MS is not sensitive to gamma-IFN or the effects of gamma-IFN are masked by other mediators induced by poly ICLC.

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The purposes of this study were to determine whether the febrile and hypotensive reactions to the administration of polyriboinosinic-polyribocytidylic acid [poly (I)-poly (C)] complexed with poly-L-lysine and carboxymethylcellulose (poly ICLC) (9S) encountered in humans could be duplicated in rabbits, and when such duplication was demonstrated, to ascertain whether these untoward reactions could be avoided by (i) administration of hydrocortisone (HC), (ii) alteration of the route of delivery, or (iii) administration of poly ICLC (4S) an interferon inducer of lower molecular weight. Responses to intravenous poly ICLC (9S) in rabbits reproduced adverse reactions in humans, namely fever and hypotension, and were accompanied by high titers of serum interferon. Continuing investigations showed that (i) intravenous pretreatment of rabbits with HC ameliorated hypotensive responses but markedly diminished interferon induction. When HC was given after poly ICLC (9S), both interferon and hypotension induction were likewise depressed. (ii) Intramuscular or subcutaneous poly ICLC (9S) produced neither high titers of serum interferon nor toxic effects. (iii) Poly ICLC (4S) induced high titers of serum interferon and fever, but no hypotension. Poly ICLC (4S) warrants further study.When megaunits of human leukocyte interferon are given to patients, interferon is potentially a potent therapeutic agent (5, 11). Unfortunately, to date, quantities of exogenous human interferon available for clinical trials are limited (7). Therefore, interferon inducers are being sought. One such promising agent is polyriboinosinic-polyribocytidylic acid [poly IC] complexed with poly-L-lysine (Miles Laboratories, Inc., Elkhart, Ind.) and carboxymethylcellulose (Hercules Powder Co., Wilmington, Del.) [poly ICLC (9S)]. This modified complex [poly ICLC (9S)], unlike the parent poly IC, is quite resistant to nucleases in primate serum and induces high titers of serum interferon in mice, monkeys, and chimpanzees. In these species, only mild deleterious effects have been noted due to the administration of poly ICLC (9S) (4,10,12,14).In a phase 1 clinical trial in humans with serious viral illnesses, poly ICLC (9S) injected intravenously (i.v.) induced high titers of serum interferon which were ordinarily somewhat higher than those produced by exogenous human leukocyte interferon. Unfortunately, fever and significant falls in blood pressure also occurred in some patients (3). To attempt to reproduce and, hopefully, ameliorate the hypotensive effects in an animal model, poly ICLC (9S) was given to rabbits, a species known to be very sensitive to poly IC. Here, we report results of initial studies with poly ICLC (9S) in rabbits, along with our initial attempts to alter favorably the toxicity which we fmd. MATERIALS AND METHODSGeneral plan of studies. Young male New Zealand white rabbits (2.5 to 3.5 kg) were obtained from Oakhill Co. (Otsego, Mich.). They were housed in individual cages (25°C) and fed standard rabbit chow (Novi Supply, Novi, Mich.) with wa...

Fourteen patients with severe viral illnesses were given intravenous infusions of a modified interferon inducer, polyriboinosinic-polyribocytidylic acid-poly-L-lysine complexed with carboxymethylcellulose [poly)I:C.LC)], during a phase 1 clinical trial. The first eight patients received 0.15 to 0.30 mg of poly(I:C.LC) per kg of body weight daily for 5 consecutive days, and another received two courses separated by 1 week. A second group of five patients was given single intravenous infusions of 0.10 to 0.15 mg of poly(I:C.LC) per kg. Interferon was detectable in the serum 8 to 16 h after injection. Titers ranged from 15 to 800 U/ml and varied directly with the dose of poly(I:C.LC). Interferonemias persisted for 12 to 48 h. In patients receiving 5-day courses of poly(I:C.LC), lower levels of serum interferon (0 to 160 U/ml) occurred on days 2 through 5, characteristic of a hyporesponsive state. An exception was a 69-year-old patient with disseminated varicella zoster, multiple myeloma, and renal insufficiency whose serum contained 3,150 U of interferon per ml on day 3 of 0.3 mg of poly(I:C.LC) per kg. Fever (39 to 40.5 degrees C, rectally; 13 of the 14 patients) peaked 3 to 8 h after completion of infusions. Other toxic effects included lymphopenia (10 of the 14 patients), hypotensive episodes (7 of the 14 patients), and minor elevations of serum glutamicoxalacetic transaminase and lactic dehydrogenase.

Stabilization of polyriboinosinic-polyribocytidylic acid against enzymatic hydrolysis by addition of poly-1-lysine and carboxymethylcellulose (PICLC) resulted in a compound with marked adjuvanticity. The primary antibody response of rhesus monkeys to formalin-inactivated Venezuelan equine encephalomyelitis virus vaccine was significantly potentiated if the vaccine was combined with PICLC prior to vaccination. The antibody response was maintained at a significantly higher level than controls for 2.5 months postvaccination and paralleled immunological responses reported for live, attenuated (TC-83) vaccine.