INHIBITION OF IGG2A(B) PRODUCTION BY IG ALLOTYPE-SPECIFIC T-CELLS CANBE MEDIATED WITHOUT T-B CELL CONTACT

The growth of IgG2a(b)-producing CB101 myeloma cells, subcutaneously o r intraperitoneally inoculated into histocompatible BALB/c Igh(a) mice sensitized against this Ig: allotype, was delayed by 2-4 weeks compar ed to normal mice, While IgG2a(b) production was detected in the sera of 75-100% of normal mice, it was irreversibly inhibited in 100% of se nsitized mice, IgG2a(b) suppression (IgG2ab sup) was also systematical ly obtained in sensitized but not normal recipients, implanted ip with a 0.1-mu m-pore diffusion chamber (DC) containing CB101 cells. This t ime, the specific IgG2a(b) sup was reversible in vitro in the absence of anti-IgG2a(b) T cells. Adoptive transfer, of unfractionated or T bu t not B splenocytes from their sensitized counterparts into normal mic e, 1 day before DC implantation, induced IgG2a(b) sup as well. These r esults indicate that, in these experimental circumstances, IgG2a(b) su p can also be mediated by diffusible suppressive factors produced by t he effector T cells, without direct T-B-cell contact. (C) 1998 Academi c Press.