An Anti-Complementary Polysaccharide With Immunological Adjuvant Activity From The Leaf Parenchyma Gel Of Aloe Vera
t’ Hart LA; van den Berg AJ; Kuis L; van Dijk H; Labadie RP
Planta Med 55(6):509-12 1989 Dec

The aim of the study is to develop new substances with immunomodulatory activity. To this end, extracts from plants used in traditional medicine are used as starting material. This study deals with the mucilagenous leaf-gel of Aloe vera which is well reputed for its therapeutical effect on inflammatory-based disorders. The purification of an aqueous gel-extract guided by inhibition of complement activity in HPS is described. Using anion-exchange and gel permeation chromatography a highly active polysaccharide fraction was isolated, that is present in the gel in various chain lengths. The polysaccharides consist of several monosaccharides of which mannose is dominant. The inhibition is based on alternative pathway activation, resulting in consumption of C3. With respect to their biological activity the polysaccharides inhibit the opsonization of zymosan in HPS and display adjuvant activity on specific antibody production and the induction of delayed type hypersensitivity in mice.

Mechanisms Of Ultraviolet Induced Immune Suppression
Strickland FM
UT MD Anderson Cancer Center
Crisp Data Base National Institutes Of Health

RPROJ/CRISP Epicutaneous exposer to ultraviolet (UV) radiation suppresses T cell-mediated immune responses to antigens encountered in the skin and permits the growth of highly immunogenic skin cancers in laboratory animals. Immune suppression by UV radiation is mediated by multiple, complex, and interacting mechanisms. Recent studies indicate the suppression is triggered by DNA damage followed by production of immunosuppressive cytokines, loss of antigen presenting cells (APC) from the skin, alteration of the functions of remaining APC, and induction of antigen-specific suppressor T cells. However, the regulation and interaction of these APC, and induction of antigen-specific suppressor T cells. However, the regulation and interaction of these APC and cytokine pathways are unclear and appears to be different for contact hypersensitivity (CHS) reactions to allergens in skin and delayed type hypersensitivity (DTH) reactions to micro-organisms. We have recently shown that crude extracts of Aloe barbadensis gel protects CHS and DTH responses against suppression by UV radiation. Because Aloe extract provides broad protection for immune responses that are abrogated by UN by different mechanisms, it may act as a central controlling point in suppression. Alternatively Aloe may contain several agents that act on CHS and DTH separately. Furthermore, Aloe is chemically distinct from antibodies, cytokines, or other agents that have been used to probe suppression pathway induced by UV radiation, and it may be acting by a novel mechanism(s). We will test these hypotheses by exposing mice to UV radiation and examining the effect of Aloe treatment on the production of the regulatory cytokines TNF-alpha, IL-10, and Il-12 in cultured keratinocyte cell liens and in skin. We will investigate whether protection of CHS and DTH responses is mediated separately by different components in Aloe. We will also examine the effect of Aloe on the function of APC from the draining lymph nodes using the murine model of CHS response to the hapten fluorescein isothiocyanate, and the DTH response to Candida albicans. In addition, we propose to investigate the ability of Aloe to preserve immunity to UV-induced skin cancers. Clarification of the relationship of the CHS and DTH models to cutaneous tumor immunity may permit the design of therapeutic agents that are more effective in protecting humans against the development of skin cancer.

Aloctin A, An Active Substance Of Aloe Arborescens Miller As An Immunomodulator
Imanishi K
Department Of Microbiology & Immunology, Tokyo Women’s Medical College
Phytotherapy Research (1993) Vol 7, No. Special issue, pp. S20-S22. 15 ref.

Aloctin A (Alo A), an active substance isolated from the leaves of A. arborescens, has many biological and pharmacological activities, such as mitogenic activity for lymphocytes, binding of human alpha 2-macroglobulin, complement activation via the alternative pathway, anti-inflammatory activity, anti-ulcer activity and antineoplastic activity. Alo A exhibited immunomodulatory activities on the immune responses of murine and human lymphoid cells in vivo and in vitro.

Immunomodulating Properties Of An Extract Isolated & Partially Purified From Aloe Vahombe Study Of Antitumoral Properties & Contribution To The Chemical Nature & Active Principle
Ralamboranto L; Rakotovao LH; Le Deaut JY; Chaussoux D; Salomon JC; Fournet B; Montreuil J; Rakotonirina-Randriambeloma PJ; Dulat C; Coulanges P
Arch Inst Pasteur Madagascar 50(1):227-56 1982

An immuno-modulator fraction (Alva) extracted from an endemic plant, in the south of Madagascar, the Aloe vahombe, significantly protects mice against bacterial, parasitic and fungal infections. Wishing to verify whether the fraction Alva was active in tumour reduction, we studied its effect on the development of experimental fibrosarcoma and melanoma in mice by intravenous and intracutaneous injections and injections directly into the tumor of the immunostimulant fraction. We have observed cures, only in the case of the McC3-1 tumor but it is encouraging to note that under different experimental conditions the rate of growth of tumors in animals which were treated is slower than in those not treated. The Alva fraction is a substance which is hydrosoluble, thermostabile, having a molecular weight exceeding 30,000 and is a polysaccharide. The predominant sugars are glucose and mannose in 3:1 ratio. Preliminary studies of its action seem to indicate that the Alva fraction acts upon nonspecific response and could possibly stimulate the phagocyte activity of the peritoneal macrophagus.