The transfer of human peripheral blood mononuclear cells (PBMC) to mice with severe combined immune deficiency (SCID) allows the investigation of immune function. The authors investigated the potential of SCID mice to produce anti-retinal antibodies from PBMC derived from retinal vasculitis patients, and in vivo primed with retinal antigen on days 2 and 22 following transfer. Using Western blotting they could not detect any anti-retinal humoral response in sera from reconstituted animals. Human CD(4)(+) or CD8(+) T cells in spleen or lymph nodes from reconstituted animals were not detected by histological examination. Similarly, no ocular pathology was apparent. The possible mechanisms involved in the lack of an anti-retinal specific antibody response in reconstituted SCID mice are discussed.