John B. Imboden

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Antibodies against the T3-antigen receptor complex can activate the human T cell line, Jurkat, to produce interleukin 2 (2-5). This activation is initiated by a receptor-mediated increase in the concentration of free cytoplasmic calcium ions [Ca2+]i (3, 4). In this communication, we investigate the mechanism by which the receptor complex increases [Ca2+ )i(More)
Rheumatoid arthritis is a chronic inflammatory polyarthritis whose etiology remains uncertain. Recently we have learned that autoimmunity to citrullinated protein antigens has specificity for rheumatoid arthritis and defines a clinically and genetically distinct form of the disease. Multiple genes contribute to disease susceptibility, with the HLA locus(More)
Similarities between the inflammatory pathways in atherosclerosis and rheumatoid arthritis (RA) are striking. Chronic systemic inflammation in RA patients leads to cardiovascular (CV) events beyond traditional cardiac risk factors. Clinicians typically focus on treating the joint manifestations of RA while neglecting to eliminate systemic inflammation,(More)
OBJECTIVE To describe the clinical and serologic abnormalities in 6 patients who presented with retiform purpura and extensive cutaneous necrosis after exposure to levamisole-adulterated cocaine. METHODS All patients were evaluated at San Francisco General Hospital or the University of California San Francisco Medical Center. Each underwent standard(More)
A monoclonal antibody to the antigen-receptor on the T cell line Jurkat induces substantial increases in [Ca++]i. Ca++ ionophores can substitute for this antibody in activation by increasing [Ca++]i to levels comparable with those seen with the antigen-receptor antibody. Stimulation with either the antigen-receptor antibody or a Ca++ ionophore leads to the(More)
Phorbol esters, such as phorbol myristate acetate (PMA), are known to be potent co-stimulants with calcium ionophores for activation of T lymphocytes. The most extensively studied intracellular effect of PMA is its ability to activate the cytoplasmic enzyme protein kinase C (pkC). Herein, we examined the role of pkC activation during T cell activation.(More)
The CD28 homodimer is thought to function as a signal transducing receptor during activation of T cells. Evidence is presented that the degree of aggregation of CD28 on the cell surface regulates two distinct CD28-associated signals. Binding of bivalent CD28 monoclonal antibody (MoAb) 9.3 upregulates lymphokine production by messenger RNA (mRNA)(More)
OBJECTIVE To determine the degree of discordance between patient and physician assessment of disease severity in a multiethnic cohort of adults with rheumatoid arthritis (RA), to explore predictors of discordance, and to examine the impact of discordance on the Disease Activity Score in 28 joints (DAS28). METHODS Adults with RA (n = 223) and their(More)
Concanavalin A (Con A), which together with phorbol myristate acetate (PMA) can activate the human T cell line Jurkat to produce interleukin 2 (IL 2), is shown to depend on the expression of the T3/T cell antigen receptor heterodimer (T3/Ti) complex to induce activation. alpha-methyl mannoside was able to reverse all of the observed effects of Con A on(More)
The human T-cell leukemia, Jurkat, and a T3-negative mutant of Jurkat (S.5) were used to study the role of T3 in human T-cell activation. Incubation of Jurkat with phytohemagglutinin (PHA) resulted in the production of interleukin 2, which was markedly increased by the addition of phorbol 12-myristate 13-acetate (PMA). Antibodies reactive with T3 could(More)