ROLE OF LIPOSOMES IN SELECTIVE PROLIFERATION OF SPLENIC LYMPHOCYTES

The effects of free and encapsulated allergens of Artemisia scoparia p ollen on lymphocyte proliferation and immunoglobulin production in BAL B/c mice were investigated. Splenic lymphocytes from mice immunized wi th liposome entrapped allergen (LEA) elicited a marked proliferative r esponse upon in vitro stimulation with both free and encapsulated alle rgen in comparison to mice immunized with free allergen (FA). The seru m immunoglobulin profile of mice administered LEA revealed a predomina nce of IgG1 antibodies concomitant with an enhancement of IgG2a, IgG2b , IgG3 and IgM responses and suppression of IgE responses. However imm unization with FA resulted in significant production of IgE responses and low levels of IgG antibodies. The differential ability of free and encapsulated allergens to selectively induce immunoglobulin isotypes suggests that different presentation and T cell differentiation pathwa ys may be followed by FA and LEA in the immune system. Proliferation s tudies involving macrophage depletion demonstrated that macrophages pl ay an obligatory role in the processing of LEA. Analysis of cytokine p roduction in sera of immunized mice (FA/LEA) revealed that LEA induced significant IFN-gamma responses and lower IL-4 responses than mice im munized with FA. The results of the present study indicate that liposo mes synergise the proliferation by the antigen incorporated in it and polarizes the response towards Thl type of cytokine production. The im munoadjuvant and immunomodulation property of liposomes make it an eff icient vehicle for effective immunotherapy.