Requirement of Thymus-dependent Lymphocytes for Potentiation by Adjuvants of Antibody Formation

Abstract

THE mode of action of immunological adjuvants is of theoretical as well as practical importance. Adjuvants can not only increase immune responses; they can also bring about change from one type of immune response to another. For example, doses of bovine serum albumin (BSA) that in the absence of adjuvant induce tolerance, in the presence of adjuvants induce antibody formation^1,2. To understand how adjuvants switch on antibody formation it may be necessary to determine which of the cells involved in the immune response are affected by adjuvants. Earlier experiments^3–5 led to the conclusion that the cells initially involved in the action of adjuvants are macrophages. This interpretation was based on observations that particulate adjuvants (such as bacteria) are ingested by macrophages but not by lymphocytes. Non-particulate or particulate adjuvants taken up by macrophages in culture and injected into syngeneic mice increased the antibody response of the recipients to two proteins (Maia squinada haemocyanin or bovine serum albumin (BSA)); in contrast, adjuvants taken up by lymphoid cells used to reconstitute immune responses in irradiated recipients had no demonstrable effect on antibody formation.