Expression of human milk fat globulin proteins in cells of haemopoietic origin

Lineage-specific gene expression has been used for the identification of me tastasis of cancers with unknown primary site or of disseminated cancer cel ls in haemopoietic compartments such as bone marrow or in lymph nodes. For the mud, cytokeratin-19 and the CEA genes, the transcription in haemopoieti c cells has been shown recently. Here, the expression of the mammary epithe lium related antigens BA46 (lactadherin) and BA70 in lymphoid and myeloid c ell lines, and in clinical specimens is analysed. By Northern-hybridization with specific oligonucleotides an ubiquitous transcription of both genes, independent from the provenance of cells or the chromosomal gender was foun d. Both mRNA molecules were amplified by rtPCR from the samples and the spe cificity could be confirmed by sequence analysis. Peptides-specific antibod ies were raised in rabbits and used for Western-blot analysis and for immun ocytochemical studies. Both antibodies reacted with total cell lysates from myeloid and lymphatic cells. In immunocytochemistry antibody P717 (anti-la ctadherin) had a significant strong staining of the myeloid cell lines K562 and HL60 suggesting a participation of lactadherin in leukocyte-function. Using antibody P718, strong stains were seen in myeloid line K562 and lymph oid line ST486. In conclusion, our findings expand the results that the con cept of lineage-specific gene expression is no longer valid at the molecula r level. (C) 2000 Cancer Research Campaign.