allogeneic bone marrow transplantation Defective activation of mitogen-activated protein kinase after

summary, rIL-2 results in significant decreases in serum IgG2 concentrations. We propose that increased NK cell numbers and increased IFN-y production are the mediators of this effect. Future studies in our SCID mouse model and in patients receiving IL-2 will address the mechanisms and clinical significance of NK regulation on human IgG2 serum concentrations. REFERENCES I. Isakson PC, Pure E, Vitteta ES, Krammer PH: T cell-derived B cell differentiation factor(s). Effect on the isotype switch of murine B cells. J Exp Med 155:734, 1982 2. Coffman RL, Carty J: T cell activity that enhances polyclonal IgE production and its inhibition by interferon-?. J Immunol 136:949, 1986 3. Snapper CM, Paul WE: Interferon-y and B cell stimulatory factor- 1 reciprocally regulate Ig isotype production. Science 236:944, 1987 4. Shurmans S, Heusser CH, Qin HY, Merino J, Brighouse G, Lambert PH: In vivo effects of anti-IL-4 monoclonal antibody on neonatal induction of tolerance and on an associated autoimmune syndrome. J Immunol 145:2465, 1990

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allogeneic bone marrow transplantation Defective activation of mitogen-activated protein kinase after

concentrations (see comments) Recombinant interleukin-2 infusions and decreased IgG2 subclass