RECOMBINANT HUMAN INTERLEUKIN 1-STIMULATED NA+/H+ EXCHANGE IS NOT REQUIRED FOR DIFFERENTIATION IN PRE-B LYMPHOCYTE CELL-LINE, 70Z/3

  • 15 March 1987
    • journal article
    • research article
    • Vol. 262  (8) , 3680-3684
Abstract
Interleukin-1 a polypeptide hormone produced by activated macrophages is a mixture of at least two proteins, interleukin-1.alpha. (IL-1.alpha.) and interleukin-1.beta. (IL-1.beta.). We have previously shown that macrophage-derived interleukin-1 induced new .kappa. light chain synthesis for surface IgM expression in a murine pre-B like cell line 70Z/3, a finding associated with an early amiloride-sensitive rise in the total intracellular sodium concentration. Because IL-1.alpha. and IL-1.beta. are structurally quite different, in this study their effect on 70Z/3 was examined separately. The results show that both human rIL-1.alpha. and rIL-1.beta. induce the differentiation of 70Z/3, but a high concentration of rIL-1.beta. compared to rIL-1.alpha. is needed for a maximal response. At saturating concentrations, both rIL-1.alpha. and rIL-1.beta. induce a simultaneous rise in intracellular pH and sodium concentration. Because rIL-1 mediated intracellular alkalinization and sodium rise are amiloride sensitive, they likely occur through stimulation of the Na+/H+ exchanger across the cell membrane. Inhibition of the Na+/H+ antiport with an amiloride analog did not have an effect on rIL-1 induce surface IgM expression or the rIL-1-mediated increase in .kappa. light chain specific mRNA level. Therefore, these results indicte that an increase in pHi or [Na]i is not required for IL-1 induced 70Z/3 differentiation.