In vitro effects of recombinant interleukin 7 on growth and differentiation of bone marrow pro-B- and pro-T-lymphocyte clones and fetal thymocyte clones.

We have studied the effects of recombinant (r) interleukin 7 (IL-7) on growth and differentiation of marrow pro-B-lymphocyte clones (CB/Bm7, LyD9, LyB9), marrow pro-T-lymphocyte clones (C4-77/3, C4-86/18, C4-95/16), and fetal thymocyte clones (FTH5, FTA2, FTD5) in the presence or absence of the bone marrow stroma clone RP.0.10, which was selected for its ability to promote differentiation of the pro-B clones. rIL-7 alone stimulated some DNA synthesis (measured by [3H]thymidine uptake) but not actual growth (increase in cell number) of the pro-B clones. Antibodies against IL-4 and IL-6 or against receptors for IL-2, IL-3, and IL-5 did not inhibit this effect of rIL-7 on the pro-B clones. rIL-7 alone or in various combinations with other cytokines (from rIL-1 alpha to rIL-6) could not induce differentiation of the pro-B clones into IgM+ B cells regardless of the presence of lipopolysaccharide (LPS). The RP.0.10 marrow stroma cells by themselves do not support the growth of the pro-B clones. However, the pro-B clones grew when cultured with rIL-7 and monolayers of the RP.0.10 stroma cells. While the RP.0.10 stroma cells induced the pro-B clones to differentiate into IgM+ B cells but not T3+ T cells when cultured in the presence of LPS and rIL-3, the B-cell progenitor clones gave rise to significantly higher numbers of IgM+ B cells (up to 63%) and to many more B cells expressing higher levels of surface IgM when cocultured with rIL-7, LPS, and RP.0.10 stroma cells. The pro-B clones also generated IgM+ B cells (up to 20%) when cocultured with RP.0.10 stroma cells and rIL-7 in the absence of LPS. By using culture plates designed for testing requirements for cell-cell contact, we found that cell interactions between the pro-B cell and the marrow stroma cell are essential to induce rearrangement and expression of the immunoglobulin genes in the pro-B clones. Possible mechanisms to account for the remarkable effects of rIL-7 in the presence of RP.0.10 stroma cells on both growth and differentiation of the pro-B clones are discussed. Finally, rIL-7 alone or together with RP.0.10 stroma cells neither supported proliferation nor induced differentiation into T3+ T cells or IgM+ B cells of the marrow pro-T clones or the fetal thymocyte clones. In light of these findings, we postulate that the interaction of the pluripotential stem cell with marrow stroma cells like RP.0.10 and the availability of IL-7 could play a critical role in the commitment to develop along the B-lymphocyte pathway.     

Temperature homeostasis in transgenic mice lacking thyroid hormone receptor-alpha gene products

We studied temperature homeostasis in male mice lacking all thyroid hormone receptor-alpha gene products (TRalpha-0/0). As other TRalpha-deficient mice, TRalpha-0/0 mice have lower core body temperature (T(C)) than cognate wild-type controls. We found that obligatory thermogenesis is normal in TRalpha-0/0 and that the lower T(C) at room temperature (RT, 20-22 C) is caused by a down setting of the hypothalamic thermostat. However, TRalpha-0/0 mice are cold intolerant due to impaired facultative thermogenesis. Norepinephrine-induced brown adipose tissue (BAT) thermogenesis is blunted, even though BAT-relevant genes and T(4) deiodinase respond normally to cold stimulation, as do serum T(3), serum glycerol (marker of lipolysis), and heart rate. BAT normally contributes to maintain T(C) at RT, 9 C below thermoneutrality, yet TRalpha-0/0 mice do not show signs of being cold stressed at 20-22 C. Instead, oxygen consumption is greater in TRalpha-0/0 than in wild-type mice at RT, suggesting the recruitment of an alternate, cold-activated form of thermogenesis to compensate for the lack of BAT thermogenesis. These results indicate that TRalpha is necessary for T(3) to modulate the central control of T(C) and for an essential step in norepinephrine activation of BAT thermogenesis but not to sustain obligatory thermogenesis. In addition, the results provide evidence for an alternate form of facultative thermogenesis, which probably originates in skeletal muscle and that is less effective and more energy demanding than BAT thermogenesis.     

Superiority of practolol versus propranolol in protection against ventricular fibrillation induced by coronary occlusion

The ability of practolol and propranolol to prevent ventricular fibrillation in experimental anterior myocardial infarction was compared in dogs subjected to ligation of the left anterior descending and first septal coronary arteries. This procedure, which causes ventricular fibrillation in 90 percent of animals within 30 minutes, was performed in control dogs and in dogs pretreated with propranolol (0.5 mg/kg body weight) or with practolol (1.5 to 2.5 mg/kg). These doses produced nearly equivalent shifts in isoproterenol-induced chronotropic dose-response curves, indicating equivalent degrees of beta adrenergic blockade. In 21 dogs with confirmed ligation, cardiogenic shock did not develop. Six of seven control dogs died with ventricular fibrillation. Six of seven dogs pretreated with propranolol also had fibrillation, whereas only one of the seven dogs pretreated with practolol manifested ventricular fibrillation during the 45 minute postligation observation period. Practolol afforded significant protection compared with no treatment or treatment with propranolol (P < 0.05).     

Clonal diseases of large granular lymphocytes [see comments]

Three distinct clinical syndromes occur in patients with increased numbers of circulating LGL. Patients with T-LGL leukemia have clonal proliferations of CD3+ LGL typically associated with chronic neutropenia and autoimmune features. NK-LGL leukemia is characterized by clonal CD3- LGL proliferation with an acute clinical presentation marked by massive hepatosplenomegaly and systemic illness. However, most patients with increased numbers of CD3- LGL do not have clinical features of NK-LGL leukemia and have a chronic clinical course. X- linked gene analyses have supported a polyclonal LGL lymphocytosis in this syndrome. Further studies are needed to determine whether clonal progression can occur in these patients.     

Nonviral delivery of self-amplifying RNA vaccines

Despite more than two decades of research and development on nucleic acid vaccines, there is still no commercial product for human use. Taking advantage of the recent innovations in systemic delivery of short interfering RNA (siRNA) using lipid nanoparticles (LNPs), we developed a self-amplifying RNA vaccine. Here we show that nonviral delivery of a 9-kb self-amplifying RNA encapsulated within an LNP substantially increased immunogenicity compared with delivery of unformulated RNA. This unique vaccine technology was found to elicit broad, potent, and protective immune responses, that were comparable to a viral delivery technology, but without the inherent limitations of viral vectors. Given the many positive attributes of nucleic acid vaccines, our results suggest that a comprehensive evaluation of nonviral technologies to deliver self-amplifying RNA vaccines is warranted.