Promyelocytic leukemia (PML) bodies are nuclear multiprotein domains. The o
bservations that viruses transcribe their genomes; adjacent to PML bodies a
nd that nascent RNA accumulates at their periphery suggest that PML bodies
function in transcription. We have used immunoFISH in primary human fibrobl
asts to determine the 3D spatial organisation of gene-rich and gene-poor ch
romosomal regions relative to PML bodies. We find a highly non-random assoc
iation of the gene-rich major histocompatibilty complex (MHC) on chromosome
6 with PML bodies. This association is specific for the centromeric end of
the MHC and extends over a genomic region of at least 1.6 megabases. We al
so show that PML association is maintained when a subsection of this region
is integrated into another chromosomal location. This is the first demonst
ration that PML bodies have specific chromosomal associations and supports
a model for PML bodies as part of a functional nuclear compartment.