IN-VIVO PRODUCTION OF VARIOUS CYTOKINES IN SPLENOCYTES OF SHEEP ERYTHROCYTE-IMMUNIZED MICE AFTER INTRAVENOUS ADMINISTRATION OF BACTERIAL LIPID-A

The effects of an intravenous administration of lipid A from Salmonell a minnesota R595 lipopolysaccharide on the in vivo production of inter leukin-2 (IL-2), IL-4, IL-5 and IL-6 in the spleens of mice intravenou sly immunized with sheep red blood cell (SRBC) antigen were investigat ed. The increased number of antigen-specific IgM antibody-producing ce lls and the titer of the IgM serum antibody were measured using the pl aque-forming cell (PFC) assay and an enzyme-linked immunosorbent assay (ELISA). Simultaneous injections of SRBC antigen and lipid A adjuvant enhanced IgM-PFC number on days 3 and 4 and the serum IgM titer on da ys 1 and 5 after the immunization. We found that the enhanced IL-4 and IL-5 levels correlated with the PFC number and IgM titer. When lipid A was injected intravenously 2 days after immunization with SRBC, the PFC number in lipid A-treated groups were similar to those in controls 3 and 4 days after the immunization. However, it was found that a two fold increase in the IgM titer in serum was induced by lipid A 5 days after immunization. In relation to this increase, lipid A stimulated t he production of only IL-5 among the cytokines tested.