THP cells? what does THP stands for?????????? - (Oct/05/2010 )

Hi all,
just a curiosity.... what does THP stands for in case of THP acute monocyte leukemic cells, i searched and searched..no details...
Please help
thanks in advance
niveda

From what I could find, it could be Tamm-Horsfall Protein 1?

This is the link to the pubmed entry for the original article, but alas it is not available online (http://www.ncbi.nlm.nih.gov/pubmed/6970727)