No abstract

Freshly isolated murine PP B cells were cultured with 10 different cytokines, including IL-1 alpha, IL-2, IL-4, IL-5, IL-6, IL-7, IFN-gamma, TNF-alpha, and TGF-beta, to investigate a possible role for these cytokines in induction of Ig synthesis. Of interest was the finding that only IL-5 and both mouse recombinant (mr) and human recombinant (hr) IL-6 enhanced IgA synthesis. The effect was greater with either mrIL-6 or hrIL-6 than with mrIL-5. IL-6 induced cycling mIgA+ PP B cells to secrete high levels of IgA (approximately 7-fold increase over control). Of importance was the finding that mrIL-6 had little effect on secretion of IgM or IgG by PP B cell cultures. hrIL-6 also increased IgA secretion by PP B cells and this enhancement was abolished by a goat anti-hrIL-6 antiserum. mrIL-6 did not cause B cell proliferation but induced a sharp increase in numbers of B cells secreting IgA. Isotype-switching was not a mechanism for this marked increase in IgA synthesis since mIgA- PP B cells were not induced to secrete IgA by mrIL-6. From these studies we conclude that IL-6 plays an important role in promoting the terminal differentiation of PP B cells to IgA-secreting plasma cells.

US troops were deployed to the Persian Gulf in what became known as the Gulf War. Upon their return, many Gulf War veterans from both the US and other allied forces began to report chronic, unexplained fatigue, pain, Author Affiliations are listed at the end of this article. Members of the VA Cooperative Study #470 Study Group and the data and safety monitoring board are listed in reference 14 of this article.

For more than a century, diabetic patients have been considered immunosuppressed due to defects in phagocytosis and microbial killing. We confirmed that diabetic mice were hypersusceptible to bacteremia caused by Gram-negative bacteria (GNB), dying at inocula nonlethal to nondiabetic mice. Contrary to the pervasive paradigm that diabetes impedes phagocytic function, the bacterial burden was no greater in diabetic mice despite excess mortality. However, diabetic mice did exhibit dramatically increased levels of proinflammatory cytokines in response to GNB infections, and immunosuppressing these cytokines with dexamethasone restored their resistance to infection, both of which are consistent with excess inflammation. Furthermore, disruption of the receptor for advanced glycation end products (RAGE), which is stimulated by heightened levels of AGEs in diabetic hosts, protected diabetic but not nondiabetic mice from GNB infection. Thus, rather than immunosuppression, diabetes drives lethal hyperinflammation in response to GNB by signaling through RAGE. As such, interventions to improve the outcomes from GNB infections should seek to suppress the immune response in diabetic hosts.

Objectives. To evaluate the safety, immunogenicity, and biologic effects of chimeric monoclonal anti‐CD4 (cM‐T412) in patients with refractory rheumatoid arthritis (RA), and to obtain preliminary data on the clinical response to this treatment.Methods. Twenty‐five patients with active refractory RA were treated with incremental doses (10 to 700 mg) of cM‐T412 in an open‐label, escalating‐dose phase I trial.Results. Infusion with cM‐T412 was followed by an immediate, rapid decline in CD4+ T cells. The level of circulating CD4+ T cells remained depressed in most patients even at 6 months posttreatment. Following antibody infusion, proliferative responses of peripheral blood lymphocytes to mitogens and antigens were determined; mitogen and antigen responses were decreased compared with pretreatment responses. Mitogen responses tended to return to baseline values more rapidly than did responses to antigen. Adverse events included fever (19 patients), which was associated with myalgias, malaise, and asymptomatic hypotension; these symptoms were self‐limited and appeared to correlate with transient elevations in interleukin‐6. No significant human antibody response to the cM‐T412 variable region was detected; only 2 patients developed transiently low levels of antibodies reactive with cM‐T412. Significant clinical improvement, defined as ≥50% decrease in tender joint counts compared with baseline, was noted in 43% of patients at 5 weeks and 33% at 6 months following cM‐T412 infusion.Conclusions. Treatment of refractory RA with cM‐T412 appears to be safe and is associated with sustained decreases in circulating CD4+ T cell counts and depressed in vitro T cell responses. No significant human antichimeric antibody response was detected. Nonblinded assessment of clinical end points suggests that treatment with cM‐T412 may have beneficial effects in these patients with refractory RA. A double‐blind clinical trial is warranted to determine its clinical efficacy in treating RA.