<i>In vitro</i> and <i>in vivo</i> Immunoadjuvant Effects of the Enzymatically Modified Fucoidan

Abstract

Objectives. No sulfated polysaccharides (fucoidans) has been declared as the pharmaceutical substances, adjuvants, etc., which is associated with the problems of obtaining the structurally characterized and homogeneous samples or their oligomeric fractions that retain high biological activity. The highly purified fucoidan with regular reproducible structural characteristics (F1) was obtained by enzymatic hydrolysis of native fucoidan (F2). Aim. The comparative study of fucoidans from the brown alga Fucus evanescens (F1 and F2) effects on the effector functions of innate and adaptive immunity cells loaded with ovalbumin (OVA) in vitro and in vivo. Material and methods. Fucoidan F1 — the enzymatically modified product of native fucoidan; F2 — the native fucoidan. The fucoidans effects on the expression level of the main immunophenotypic markers of innate and adaptive immunity (neutrophils, monocytes, natural killers, lymphocytes) cells in vitro were studied by methods of flow cytometry. The fucoidans effects on the production of serum OVA-specific antibodies (IgG, IgG1, IgG2а) and cytokines (IFNγ, IL-2, IL-10, IL-12) were detected in BALB/c mice immunized with OVA. Results. The tested fucoidans activate the effector functions of innate and adaptive immunity cells loaded with OVA in vitro and act as adjuvants, stimulating both Th1 (IgG2а, INFγ, IL-2) and Th2 (IgG1, IL-10) immune response to OVA in vivo. Conclusions. The immunoadjuvant effect of the enzymatically modified fucoidan (F1) on effector functions of innate and adaptive immunity cells are comparable to those of the native fucoidan (F2). The findings determine the possibility of F1 use as an adjuvant for a wide range of prophylactic and therapeutic vaccines.