Diminished percentage of antigen bearing cells in the lymph nodes of immune aged rats

We have demonstrated previously that during experimental autoimmune prostat itis (EAP), aged rats show a diminished humoral autoimmune response. In the present paper we have studied the transport of the autoantigen from the si te of injection toward lymphatic organs in rats of different ages with or w ithout EAP. We used as autoantigen prostatic components (rat accessory glan ds (RAG)) conjugated with fluorescein isothiocyanate (FITC). Studies of flo w cytometry, fluorescent microscopy and confocal microscopy show no differe nces in the percentage of RAG-FITC positive cells or in the localization of the cells in the popliteal lymph nodes of not-immunized young and aged rat s. On the other hand, in 18-month-old rats immunized with either RAG or Ova lbumin there were lower levels of specific IgG antibodies and fewer antigen containing cells in the draining lymph nodes than those of 3- or 12-month- old rats. In all groups fluorescent cells were MHC class II positive and so me were IgM positive. Our results demonstrate that in immunized 18-month-ol d rats there is a diminished percentage of cells bearing the antigen in the draining lymph nodes after antigen injection in the skin, related to the l evels of specific antibodies able to form antigen-antibody complexes in the periphery. (C) 2001 Elsevier Science Inc. All rights reserved.