Resumen de The distribution, immune complex trapping ability and morphology of follicular dendritic cells in popliteal lymph nodes of aged rats
Immune system function declines with age, and lymph nodes involute. The aims of the study were to descri be th e d istributio n of fo llic ul ar de nd riti c ce lls (FOCs) in the lympho id fo llic les of aged rats, and to de term ine whether these cells have reduced abilit y to trap immune complexes (ICs). Popliteal lymph nodes of rats aged 24-28 mo nths we re immunostained for S-lOO protein as a marker of FOCs. Some rats we re pretreated w ith perox idase -ant i-perox idase compl ex (PA P) as an Ie. FOCs we re densely distributed in lymphoid follicles, w hi c h co nt a in ed ma ny prima ry fo lli c les a nd a few secondary fo llicles. FOCs in primary fo llicles stai ned weakl y for S-1 00 protein , and showed weak trapping, whil e those in secondary fo llicles stained strong ly fo r both S-\ OO prote in and trapping . Ultrastructurall y, in involuted lympho id follicles FOCs were atro phic. We conclude that FOCs in aged rats are de nse ly distributed in involuted follicles and show reduced trapping ability and atrophic morphology. This seems to retlect the long life of FOCs and the reduced numbers of lymphoid cells in these foll icles. We suggest that FOCs in aged rats may show some of their normal functio ns if full y deve loped ge rmin a l ce nt e rs a re indu ce d , and may no t pl ay a n impo rt a nt ro le in th e p rocess of in vo luti o n of th e follicles
