SUPPRESSIVE EFFECT OF INTRAVENOUS IMMUNOGLOBULINS ON THE ACTIVITY OF INTERLEUKIN-1

In order to study the effect of human immunoglobulin preparations for intravenous use (IVIg) on the production and activity of interleukin-1 (IL-1) derived from monocytes, we treated cultured monocytes with IVI g and examined the lymphocyte-activating factor (LAF) activity of IL-1 in the culture supernatants. The results showed that IVIg suppressed the activity from most healthy adults and some febrile children with a cute respiratory disease or Kawasaki disease. Further studies revealed that intact Ig (whole molecular Ig) did not suppress the mRNA express ion of IL-1 alpha or IL- 1 beta in mononuclear cells, that intact Ig a nd pepsin-digested Ig inhibited the LAF activity of recombinant IL-1 ( rIL-1) and also that intact Ig contains immunoglobulin (probably anti- IL-1 antibody) which binds with rIL-1 by dot blotting using biotin-str eptavidin. These results suggest that IVIg suppresses neither IL-1 syn thesis nor the release of IL-1 from monocytes but does neutralize IL-l a and IL-1 beta activity by binding IL-1 proteins as an anti-IL-1 anti body.