Organ distribution of proteinase-resistant prion protein in humans and mice with Creutzfeldt-Jakob disease

We attempted to clarify the organ distribution of human and murine proteinase-resistant prion protein [PrP(CJD)] in Creutzfeldt-Jakob disease (CJD), and to measure the concentration of PrP(CJD), using a semi-quantitative Western blot analysis. Human PrP(CJD) was restricted to the central nervous system, whereas murine PrP(CJD) was present in the central nervous system and in the lymphoreticular system at the end stage of CJD. PrP(CJD) concentration in the central nervous system of mice was almost identical to that of humans. The minimum wet weight of an organ with a positive reaction was 0.3 mg for brain, 1 to 3 mg for spleen, 3 mg for spinal cord, 3 mg for lymph node, 10 mg for thymus and 10 to 30 mg for intestine of the CJD-infected mice. There were no immunoreactions in purified PrP(CJD) fractions from 300 mg of spleen, lymph node, liver or peripheral nervous systems of humans, nor in 300 mg of liver, lung or kidney of CJD-infeced mice. Within the limits of our method, the distribution of murine PrP(CJD) differed from that of human PrP(CJD). Antibodies on the Western blot membrane from murine spleen PrP(CJD) fractions stained the kuru plaques in the CJD-infected mouse brain. Therefore, PrP(CJD) in the murine spleen probably shares the epitopes of the antigen in the murine kuru plaques. Although the immunological detection of PrP(CJD) does have limits of sensitivity, PrP(CJD) concentrations did correlated with infectivity titres in scrapie-infected or CJD-infected mice.