COMPARISON BETWEEN THE PHENOTYPE AND FUNCTION OF MATURING DENDRITIC CELLS FROM SPLEEN AND LYMPH-NODES

We compared the capacity of mature dendritic cells (DC) from lymph nod es and maturing DC from spleens in their capacity to stimulate respons es to the small hapten picryl sulphonic acid (PIC) and to the same hap ten conjugated to ovalbumin (PIC-OVA) and requiring processing. Surfac e expression of major histocompatibility complex (MHC) class II molecu les, which are upregulated during maturation of splenic DC, were studi ed as an independent marker of maturation. Freshly isolated lymph node DC had a veiled appearance and high levels of class II expression. DC separated from suspensions of spleen cells expressed the DC-specific marker NLDC-145, but were small, had low levels of MHC class II molecu les and expressed stem cell antigen. Those DC from spleen cells cultur ed for 24 and 48 hr showed the development of typical veiled DC morpho logy and high class II expression. Lymph node DC stimulated high level s of primary T-cell proliferation to PIC, but failed to stimulate prim ary responses to PIC-OVA. Splenic DC isolated immediately failed to st imulate primary responses to either antigen. More mature spleen DC sti mulated responses both to PIC and PIC-OVA. Surprisingly, development o f the capacity to stimulate responses to PIC preceded that of stimulat ing PIC-OVA responses. The capacity of the DC to process and present P IC-OVA was maintained during the culture period. The results indicate that both the form of the antigen and the source and maturity of the D C are critical in determining the responses stimulated in T lymphocyte s.