AUTOANTIBODIES AGAINST H-SUBUNITS AND M-SUBUNITS OF NEUROFILAMENTS ARE INDUCED BY PC12 CELL GRAFTS OR LESIONS INTO DIFFERENT SITES OF RAT-BRAIN

Since autoantibodies against neurofilaments (NF) were frequently found in neurodegenerative disorders, this work is an attempt to investigat e whether the same phenomenon occurs after intracerebral grafting or l esioning. We have thus either grafted PC12 cells or injected culture m edium alone into three sites of rat central nervous system (CNS): olfa ctory bulb (OB), olfactory anterior nucleus (OAN) and hippocampus (HC) , all three sites being impaired in Alzheimer's disease. At day 15, ra t sera were collected and tested against NF by western blotting. Sera from grafted rats recognized the H- and M-subunits of NF; we have then quantified the autoantibody response by using an ELISA technique. We show that, in all cases of grafts, the autoantibody response against N F significantly increased when compared to controls (normal rats witho ut grafts or lesions) for total immunoglobulin (Ig) amount. In contras t, concerning the Ig isotypes, some differences appeared depending on the implantation site: for grafts into OB, the immune response was of both the IgG and IgM isotypes, into OAN it was mainly of the IgM isoty pe and into HC, the isotype of antibodies against NF was mostly IgG. I n the case of lesions alone into OAN and HC, no significant enhancemen t of autoantibody response was observed; in contrast, lesions into OB induced an increase in autoantibody response against NF which signific antly differed from controls for all Ig isotypes tested. These data po int out the diversity of the autoantibody responses following lesions or grafts according to the rat brain areas.