Effect of immunological adjuvants on the appearance of monocyte and dendritic cell precursors in rat thoracic duct lymph.

Abstract

Successful induction of immune responses to thymic-dependent antigens such as sheep erythrocytes are absolutely dependent upon histocompatible, nonlymphoid antigen-presenting cells (1–3). Although thoracic duct lymph (TDL) exhibits less in vitro stimulatory activity than whole spleen cells (4), various in vitro and in vivo immune phenomena attributed to TDL suggest that antigen-presenting cells or their precursors must be present in normal TDL (5–7). This report describes adherent cell types in TDL of normal (8) and adjuvant-treated Lewis rats. The results indicate that macrophages and nonphagocytic dendritic cells differentiate in culture from small cells in TDL. These precursors pass through nylon wool and G-10 columns. Both cell types bear Ia-antigens but differ from each other with respect to complement and Fc receptor expression. Treatment with either complete Freund’s adjuvant (CFA) or a new lipoidal amine adjuvant CP-20, 961 (Pfizer) (9,10) increases the TDL output of both cells. One of the mechanisms of adjuvant action might be production and dissemination of precursors of antigen-presenting cells that complete differentiation in peripheral lymphoid tissues and provide continued antigenic stimulation for lodging daughter cells (11–13).