LANGERHANS CELLS DO NOT EXPRESS ALTERNATIVE MACROPHAGE ACTIVATION-ASSOCIATED CC-CHEMOKINE (AMAC)-1

We have cloned a novel human CC chemokine, alternative macrophage acti vation-associated CC chemokine (AMAC)-1 that is highly homologous to m acrophage inflammatory protein (MIP)-1 alpha. In contrast to MIP-1 alp ha AMAC-1 is induced in macrophages by Th2-associated cytokines IL4, I L13, and IL10 in vitro; in addition, AMAC-1 is expressed by Th1-suppre ssive alveolar macrophages in vivo. Surprisingly, however, AMAC-1 is a lso expressed by GM-CSF-induced, in vitro monocyte-derived dendritic c ells when treated by IL4. Here, we present a detailed analysis of AMAC -1 expression in monocyte-derived dendritic cells in vitro and show th at the prime dendritic cells in vivo, i.e. epidermal Langerhans cells, do not express AMAC-1 mRNA. In conclusion, AMAC-1 is a novel CC chemo kine whose Th2-associated expression pattern in alternatively activate d suppressor macrophages in vivo and in vitro and its absence from epi dermal Langerhans cells in vivo suggest that it may be involved in inh ibition of Th1 reactions and in tolerance induction.