Studies of superglacial debris on valley glaciers

Abstract

IL-4-dependent and -independent IgG1 Abs differ in their ability to induce mast cell degranulation as measured by passive cutaneous anaphylaxis (PCA). Mice immunized with OVA or PIII (fraction of <i>Ascaris suum</i>) produced high titers of IgG1 as shown by ELISA and PCA. In contrast, another <i>A. suum</i> fraction, PI, elicited IgG1 Abs with no PCA activity. IgG1 with anaphylactic activity required IL-4, as IgG1 responses to OVA and PIII in IL-4^−/− mice gave no PCA. PI-specific IgG1 was IL-4-independent, because no difference was found between the responses of IL-4^−/− and IL-4^+/+ mice. Significant PCA reactions were elicited, however, with PI-specific IgG1 from IL-12^−/− or anti-IFN-γ Ab-treated mice, although less Ab was measured by ELISA. These results indicate that one type of IgG1 has anaphylactic activity and its synthesis is IL-4-dependent, being inhibited by IL-12 or IFN-γ; the other lacks this activity and its synthesis is stimulated by IL-12 or IFN-γ.