RETROVIRUS-INDUCED IMMUNOSUPPRESSION VIA BLOCKING OF DENDRITIC CELL-MIGRATION AND DOWN-REGULATION OF ADHESION MOLECULES

Dendritic cells (DC) within tissues may acquire and process antigens, carry them into lymph nodes and cluster and activate T cells. The abil ity of DC to acquire antigen and to migrate to lymph nodes was estimat ed during murine retroviral infection caused by Rauscher leukaemia vir us (RLV). A novel mechanism of inducing immunodeficiency has now been identified. In mice infected with RLV, DC failed to migrate into lymph nodes following exposure of the skin to the contact sensitizer, fluor escein isothiocyanate. RLV infection of a proportion of DC both in ski n and lymph nodes, shown by semi-quantitative polymerase chain reactio n (PCR) and downregulation of expression of adhesion molecules (CD54 a nd CD44) on the surface of Langerhans' cells, may contribute to the de scribed phenomenon. A failure of DC migration could be an important im munosuppressive mechanism of RLV infection in mice and we speculate on a similar role for DC in human immunodeficiency virus-1 (HIV-1) infec tion in humans.