Laboratoire d'lmmunologie Cellulaire et Clinique, INSERM U.255, Institut Curie, Paris Recombinant interleukin 2-activated natural killer cells regulate IgGza production*
In this report we have analyzed the effect ofrecombinant interleukin 2 (rIL 2) and rIL 2-activated natural killer (NK) cells on the production of immunoglobulin isotypes by lipopolysaccharide (LPS)-stimulated spleen cells from nude mice. We found that rIL 2 induced a dose-dependent increase of IgG2, secretion and a concomitant inhibition of the secretion of other Ig isotypes. The analysis of the phenotype of LPS-and LPS+rIL 2-stimulated nude spleen cells showed the appearance of a Thy-l+asialo GM-l+slgM-CD3-CD4-CD8-cell population in the presence of rIL 2. A population with a similar phenotype was generated upon stimulation of spleen cells from nude mice with rIL 2 alone. These cells lysed YAC-1 cells, did not contain the a or y transcripts encoding the corresponding T cell receptor chains and are therefore NK cells activated by rIL 2. In co-culture experiments, these cells selectively increased the secretion of IgG2, by LPSstimulated splenocytes from nude mice. The IgG2, induction triggered by rIL 2-activated NK cells, as well as that triggered by rIL2, were blocked by an anti-interferon y monoclonal antibody. Thus, rIL 2 activated-NK cells enhance the production of IgG2, by secreting interferon-y.