Desulfated carrageenans and cytotoxicity of human monocytes.

Abstract

Carrageenan is a high molecular weight sulfated polygalactose extracted from the marine algae Chondrus cripsus and has several biological and immunological properties. There are three kinds of carrageenans (CGNs)2 available. They are kappa, lambda and iota CGN. Almost all sulfate groups of kappa and iota CGN were removed with acid-methanol treatment and about half of the sulfate groups of lambda CGN were depleted by the same method. We obtained the following data, using CGNs and sulfatedepleted CGNs. (1) CGNs and sulfate-depleted CGNs were toxic to human monocytes and sulfate-depleted kappa and iota CGN were more toxic to monocytes than kappa and iota CGN, as judged by a method of Stewart and Ingram. (2) When sulfate-depleted kappa and iota CGN were added at the doses of 100 μg/ml, 500 μg/ml and 1 mg/ml to mononuclear cells (MNC) and autologous and allogeneic MLR, the proliferative responses were not induced. When lambda CGN, whose sulfate groups were partially depleted were added at the doses of 100 μg/ml, 500 μg/ml and 1 mg/ml there was still a moderate response. (3) However, the capacity to kill monocytes by sulfatedepleted CGNs was well preserved and kappa and iota CGN, whose sulfate groups were totally removed, was also slightly toxic to lymphocytes at more than 6 days of culture. (4) They can be used as macrophage-toxic agents by decreasing the dose up to 100 μg/ml, which is really lacking in mitogenicity and lymphocyte toxicity.