Galactosylcerebrosidase activity in tissues of twitcher mice with and without bone marrow transplantation.

Galactosylcerebrosidase activity was measured and compared in brain, liver, tongue and bone marrow of twitcher (twi/twi) mice, an animal model of human Krabbe's disease, and in normal heterozygotes (twi/+). There was a reduction in enzyme activity in all tissues in twi/twi mice, but the magnitude of the reduction varied, being greatest in the bone marrow (3% of the heterozygote activity). Twitcher mice were transplanted with normal bone marrow cells at birth without prior irradiation, and just over half had a significant increase in their bone marrow enzyme activity, but not in other tissues. The fourfold increase in the enzyme activity was not associated with any improvement in the clinical picture or prolongation of lifespan.