Monocytes control gamma/delta T-cell responses by a secreted product

Gamma-irradiated ex vivo bovine monocytes induce proliferation of gamma/delta T cells in the autologous mixed lymphocyte reaction (AMLR), whereas when not irradiated they prevent this response. In contrast, non-irradiated autologous monocytes have no effect on bovine alpha/beta T-cell proliferation in the allogenic MLR suggesting that the regulation is specific for gamma/delta T-cell responses. Here, we showed that the inhibition was not mediated by inducing cell death and that the ability of ex vivo monocytes to prevent proliferation of gamma/delta T cells was not generalized in that gamma/delta T cells still responded to mitogenic stimulation. Inhibition of the AMLR by non-irradiated monocytes could not be overcome by addition of interleukin-2 to the cultures or by costimulation with antibodies to WC1, a gamma/delta T-cell-specific cell-surface differentiation antigen shown elsewhere by us to be involved in activation of gamma/delta T cells. Furthermore, we showed that monocytes inhibited gamma/delta T-cell responses via a soluble product since inhibition occurred even when monocytes and gamma/delta T cells were separated by membranes of transwells or when supernatants from monocyte cultures were added to AMLR cultures. Maximal secretion of the inhibitory product by the monocytes occurred during the first 6 hr of in vitro culture at 37 degrees, rapidly decreased thereafter, and did not occur when monocytes were incubated at 4 degrees. The inhibition was not attributable to nitric oxide, reactive oxygen intermediates, prostaglandin E2 or transforming growth factor-beta (TGF-beta) but the ability of monocyte supernatants to mediate inhibition was sensitive to heating at 65 degrees. Lipopolysaccharide and granulocyte-macrophage colony-stimulating factor activation of monocytes temporarily abrogated their ability to inhibit proliferation. In contrast, heat-shocking had no effect on their ability to inhibit. We hypothesize that non-irradiated monocytes produce the inhibitory material in vivo in order to regulate gamma/delta T-cell responses to self-derived monocyte membrane components, but that when monocytes are altered by infection, transformation, irradiation, or cytokine activation, production of the inhibitor is temporarily suspended allowing stimulation of gamma/delta T cells to occur.     

Antibodies to soluble liver antigen, P450IID6, and mitochondrial complexes in chronic hepatitis

BACKGROUND: Antibodies to soluble liver antigen, P450IID6, and the E2 subunits of mitochondrial dehydrogenase complexes occur in autoimmune liver diseases, but their specificities and implications are uncertain. The aims of the present study were to assess the importance of these autoantibodies in different types of chronic hepatitis. METHODS: Sera from 62 patients with autoimmune hepatitis, 37 patients with cryptogenic hepatitis, and 19 patients with chronic hepatitis C were assessed under code by enzyme immunoassay. RESULTS: Antibodies to soluble liver antigen were found in 7 patients with autoimmune hepatitis (11%) and 5 patients with cryptogenic disease (14%). Patients with antibodies to soluble liver antigen were indistinguishable from seronegative counterparts with autoimmune hepatitis. Seropositive patients with cryptogenic hepatitis had autoimmune features, and they responded to corticosteroid therapy. Five patients (8%) with autoimmune hepatitis were seropositive for antibodies to mitochondrial complexes. Three lacked antimitochondrial antibodies. None of the patients had antibodies to P450IID6, and patients with chronic hepatitis C were seronegative for all markers. CONCLUSIONS: Antibodies to soluble liver antigen do not define a distinct subgroup of patients with autoimmune hepatitis. They may be found in some patients with corticosteroid-responsive cryptogenic hepatitis. Antibodies to E2 subunits and P450IID6 are uncommon in adults with chronic hepatitis.     

In vivo characterization of sustained-release formulations of human growth hormone

Long-acting formulations of recombinant human growth hormone (rhGH) were prepared by stabilizing and encapsulating the protein into three different injectable, biodegradable microsphere formulations composed of polymers of lactic and glycolic acid. The formulations were compared in juvenile rhesus monkeys by measuring the serum levels of rhGH and two proteins induced by hGH, insulin-like growth factor-I and IGF binding protein-3 (IGFBP-3) after single s.c. administration. All three formulations, which differed principally in the composition of the polymer, provided sustained elevated levels of all three proteins for several weeks, and the rate of release of rhGH differed among the formulations consistent with the molecular weight of the polymer used. All three formulations induced a higher level of insulin-like growth factor-I and insulin-like growth factor binding protein than was induced by daily injections of the same amount of rhGH in solution. After three monthly injections of one of the formulations, both the rhGH and IGF-I levels remained elevated for nearly 90 days. Immunogenicity of the rhGH released from this formulation, as assessed by the incidence of seroconversion to hGH and the titer of anti-hGH antibody in both the rhesus monkeys and transgenic mice expressing rhGH, was no greater than that of the unencapsulated protein. In addition, the microsphere injection sites appeared normal by macroscopic evaluation between 1 to 2 mo after microsphere administration and by microscopic evaluation between 2 to 3 mo. These results show that serum levels of a therapeutic protein can be sustained for an extended period when encapsulated into different formulations of injectable, biodegradable microspheres.