The proximate cause of autoantibodies characteristic of systemic autoimmune diseases has been controversial. One hypothesis is that autoantibodies are the result of polyclonal nonspecific B cell activation. Alternatively, autoantibodies could be the result of antigen-driven B cell activation, as observed in secondary immune responses. We have approached this question by studying monoclonal anti-DNA autoantibodies derived from unmanipulated spleen cells of the autoimmune MRL/lpr mouse strain. This analysis shows that anti-DNAs, like rheumatoid factors (19), are the result of specific antigen-driven stimulation. In addition, correlation of sequences with fine specificity shows that: (a) somatic mutations can cause specificity for dsDNA and that such mutations are selected for; (b) arginine residues play an important role in determining specificity; and (c) anti-idiotypes that recognize the majority of anti-DNA are probably not specific for any one family of V regions.

Pl(A2)-positive platelets displayed a lower threshold for activation, and platelets heterozygous for Pl(A) alleles showed increased sensitivity to 2 antiplatelet drugs. These in vitro platelet studies may have relevance for in vivo thrombotic conditions.

The potential therapeutic activity of a human monoclonal antibody to the human interleukin-12 p40 subunit (anti-IL-12p40) has been established both in vitro and in vivo, warranting a first-in-human investigation in psoriasis. This phase I, first-in-human, non-randomized, open-label study evaluated the short-term safety, pharmacokinetics, and clinical response of single, ascending, intravenous (IV) doses of anti-IL-12p40 in subjects with moderate-to-severe psoriasis vulgaris. Eighteen subjects with at least 3% body surface area involvement were enrolled in four dose groups (0.1, 0.3, 1.0, and 5.0 mg per kg). Safety, pharmacokinetics, and clinical response (e.g., Psoriasis Area and Severity Index (PASI)) were monitored at baseline and at specific time points over a 16-wk follow-up period. Anti-IL-12p40 was generally well tolerated. No related serious adverse events or infusion reactions were reported, and most adverse events were mild. IV anti-IL-12p40 yielded linear pharmacokinetics, with a mean terminal half-life of approximately 24 d. Dose-dependent associations with both the rate and extent of clinical response were observed across the four dose groups. Twelve of 18 subjects (67%) achieved at least a 75% improvement in PASI between 8 and 16 wk after study agent administration. Significant and sustained concentration-dependent improvements in psoriatic lesions were observed in most subjects.

Psoriasis is characterized by activation of T cells with a type 1 cytokine profile. IL-12 and IL-23 produced by APCs are essential for inducing Th1 effector cells. Promising clinical results of administration of an Ab specific for the p40 subunit of IL-12 and IL-23 (anti-IL-12p40) have been reported recently. This study evaluated histological changes and mRNA expression of relevant cytokines and chemokines in psoriatic skin lesions following a single administration of anti-IL-12p40, using immunohistochemistry and real-time RT-PCR. Expression levels of type 1 cytokine (IFN-γ) and chemokines (IL-8, IFN-γ-inducible protein-10, and MCP-1) were significantly reduced at 2 wk posttreatment. The rapid decrease of these expression levels preceded clinical response and histologic changes. Interestingly, the level of an anti-inflammatory cytokine, IL-10, was also significantly reduced. Significant reductions in TNF-α levels and infiltrating T cells were observed in high responders (improvement in clinical score, ≥75% at 16 wk), but not in low responders. Of importance, the levels of APC cytokines, IL-12p40 and IL-23p19, were significantly decreased in both responder populations, with larger decreases in high responders. In addition, baseline levels of TNF-α significantly correlated with the clinical improvement at 16 wk, suggesting that these levels may predict therapeutic responsiveness to anti-IL-12p40. Thus, in a human Th1-mediated disease, blockade of APC cytokines by anti-IL-12p40 down-regulates expression of type 1 cytokines and chemokines that are downstream of IL-12/IL-23, and also IL-12/IL-23 themselves, with a pattern indicative of coordinated deactivation of APCs and Th1 cells.

These results are consistent with continuous reequilibration of abciximab among circulating platelets and may explain the gradual recovery of platelet function and long-term prevention of ischemic complications by abciximab after coronary intervention.

A large number of glycoprotein (GP) IIb/IIIa receptors are present on the surface of platelets. Studies to define precisely the number of GPIIb/IIIa receptors using specific monoclonal antibodies (MoAbs) or fibrinogen binding have, however, yielded varying estimates of receptor number. To refine the quantitative estimation of GPIIb/IIIa receptors on resting platelets, we have used the MoAb 7E3, which has high affinity for GPIIb/IIIa. Quantitative binding studies were performed using radiolabeled conjugates of 7E3 IgG, as well as fragments and derivatives of 7E3. For platelets obtained from any single individual, the numbers of 7E3 F(ab′)2 and IgG molecules bound per platelet were equivalent (approximately 40,000), whereas the number of Fab molecules bound per platelet was consistently approximately twofold higher (approximately 80,000). To investigate the basis of the quantitative disparity in binding of intact 7E3 and 7E3 F(ab′)2 versus 7E3 Fab, we studied the binding of a newly constructed, bispecific (Fab′)2 molecule containing only a single 7E3 combining site. Because this construct bound to the same extent as the Fab species, the larger size of the intact 7E3 and 7E3 F(ab′)2 molecules could not explain the reduced number of molecules that bound per platelet compared to the Fab fragment. Rather, it appears that the valency of the antibody is the critical factor determining the number of antibody molecules bound per platelet. Thus, we conclude that the binding of 7E3 Fab corresponds most closely with surface GPIIb/IIIa number and that the number of GPIIb/IIIa receptors is approximately 80,000 per platelet.

Purpose: Approximately two-thirds of patients with the lysosomal storage disease mucopolysaccharidosis II have progressive cognitive impairment. Intravenous (i.v.) enzyme replacement therapy does not affect cognitive impairment because recombinant iduronate-2-sulfatase (idursulfase) does not penetrate the blood-brain barrier at therapeutic concentrations. We examined the safety of idursulfase formulated for intrathecal administration (idursulfase-IT) via intrathecal drug delivery device (IDDD). A secondary endpoint was change in concentration of glycosaminoglycans in cerebrospinal fluid. Methods:Sixteen cognitively impaired males with mucopolysaccharidosis II who were previously treated with weekly i.v. idursulfase 0.5 mg/ kg for ≥6 months were enrolled. Patients were randomized to no treatment or 10-mg, 30-mg, or 1-mg idursulfase-IT monthly for 6 months (four patients per group) while continuing i.v. idursulfase weekly. Results:No serious adverse events related to idursulfase-IT were observed. Surgical revision/removal of the IDDD was required in 6 of 12 patients. Twelve total doses were administrated by lumbar puncture. Mean cerebrospinal fluid glycosaminoglycan concentration was reduced by approximately 90% in the 10-mg and 30-mg groups and approximately 80% in the 1-mg group after 6 months. Conclusions:These preliminary data support further development of investigational idursulfase-IT in MPS II patients with the severe phenotype who have progressed only to a mild-to-moderate level of cognitive impairment.

Golimumab is a fully human antitumor necrosis factor alpha (TNF-alpha) monoclonal antibody that is being developed for intravenous and subcutaneous administration. To assess the pharmacokinetics and safety of the intravenous formulation of golimumab, 36 adult subjects with rheumatoid arthritis were randomly assigned to receive a single infusion of placebo or golimumab (0.1, 0.3, 1, 3, 6, or 10 mg/kg). Serum concentrations of golimumab were determined using a validated enzyme-linked immunosorbent assay method. In addition to the noncompartmental analysis and compartmental modeling, a population pharmacokinetics analysis using NONMEM was also conducted. Both the maximum serum concentration and the area under the serum concentrationtime curve appeared to increase in a dose-proportional manner. The median half-life ranged from 7 to 20 days. A 2-compartment population pharmacokinetic model adequately described the pharmacokinetics of golimumab. The following pharmacokinetic parameters (typical value [% coefficient of variation]) were estimated from the population pharmacokinetic model: clearance (CL: 0.40 [10.1%] L/d), volume of distribution in the central compartment (V(c): 3.07 [6.4%] L), intercompartmental clearance (Q: 0.42 [15.5%] L/d), and volume of distribution in the peripheral compartment (V(p): 3.68 [11.8%] L). Interindividual variability of the pharmacokinetic parameters was quantified for CL (44.3%), V(c) (25.5%), Q (44.6%), and V(p) (44.6%). Residual variability was estimated to be 15.0%. Body weight was found to be an important covariate on V(c). Golimumab was generally well tolerated. The pharmacokinetics of golimumab appeared to be linear over the dose range evaluated in this study.