In situ processing and distribution of intracerebrally injected OVA in the CNS.

Drainage and retention of brain-derived antigens are important factors in initiating and regulating immune responses in the central nervous system (CNS). We investigated distribution, immunological processing and retention of intracerebrally infused protein antigen, ovalbumin (OVA), and the subsequent recruitment of CD8(+) T cells into the CNS. We found that protein antigens infused into the CNS can drain rapidly into the cervical lymph node and initiate antigen-specific immune response in the periphery. A portion of the antigens are also retained by CD11b/MAC-1(+) cells in the brain parenchyma where they are recognized by antigen-specific CD8(+) T cells.