Lymphocyte activation by a polysaccharide fraction separated from hot water extracts of Angelica acutiloba Kitagawa.

The action of a polysaccharide fraction obtained from hot water extracts of Angelica acutiloba Kitagawa, termed as Angelica immunostimulating polysaccharide (AIP) fraction, on murine lymphocytes participating in antibody responses was investigated. When AIP fraction was injected concomitantly into mice immunized with antigens, immunoglobulin M (IgM) and IgG antibody responses against sheep erythrocytes (SRBC) increased significantly, but IgM response against T-independent antigens such as trinitrophenylated lipopolysaccharide (TNP-LPS) and TNP-Ficoll did not augment. Murine B lymphocytes were polyclonally activated in vitro and in vivo by AIP fraction to differentiate into antibody-forming cells as functionally matured cells. The differentiation of B lymphocytes to an intermediate stage capable of responding to helper T lymphocytes was also stimulated by the administration of AIP fraction into CDF1 and C3H/HeJ mice. A concomitant injection of AIP fraction with SRBC for carrier priming resulted in the increment of anti-TNP IgM antibody response in cultured reconstituted with unprimed B and SRBC-primed T lymphocytes, indicating that AIP fraction can stimulate T lymphocytes.