Is it wrong to deconvolute bulk RNA seq data of a tissue using scRNAseq data of a different tissue?

[Tushar-87]

I am interested in knowing if PBMCs infiltrate into the brain. I want to deconvolute bulk RNA seq data of human brain using single cell data of human PBMCs. Does it make sense to do this? If some cell types in the input single cell data are absent from the tissue from which we generated bulk RNAseq data, then we should have zero values for these cell types after deconvolution. Is this true?