Effects of the B-cell activators lipid A and dextran sulphate on the antibody response to sheep red blood cells in piglets.

The in vivo effects of Lipid A and dextran sulphate on the antibody response to the thymus-dependent antigen SRBC in piglets are reported. No alteration of the low primary antibody response was observed with any of the B-cell activators. However, both substances induced an increase in antibody titre after secondary challenge with the antigen, which was shown to be of the IgG class. An activation of immunological memory in the absence of primary antibody response is suggested.