ORGAN INVOLVEMENT AND PHENOTYPIC ADHESION PROFILE OF 5T2 AND 5T33 MYELOMA CELLS IN THE C57BL KALWRIJ MOUSE/

The aim of this study was to evaluate the tissue infiltration and phen otypic adhesion profile of 5T2 multiple myeloma (MM) and 5T33 MM cells and to correlate it with that observed in human disease. For each lin e, 30 mice were intravenously inoculated with myeloma cells and at a c lear-cut demonstrable serum paraprotein concentration; mice were sacri ficed and a number of organs removed. The haematoxylin-eosin stainings on paraffin sections were complemented with immunohistochemistry usin g monoclonal antibodies developed against the specific MM idiotype. Wh en analysed over time, 5T2 MM cells could be observed in bone marrow s amples from week 9 after transfer of the cells. For the 5T33 MM, a sim ultaneous infiltration was observed in bone marrow, spleen and river 2 weeks after inoculation. Osteolytic lesions consistently developed in the 5T2 MM, but this was not consistent for 5T33 MM. PCNA staining sh owed a higher proliferative index for the 5T33 MM cells. The expressio n of adhesion molecules was analysed by immunohistochemistry on cytosm ears: both 5T2 MM and 5T33 MM cells were LFA-1, CD44, VLA-4 and VLA-5 positive. We conclude that both lines have a phenotypic adhesion profi le analogous to that of human MM cells. As the 5T2 MM cells are less a ggressive than the 5T33 MM cells, their organ distribution is more res tricted to the bone marrow and osteolytic lesions are consistently pre sent, the former cell line induces myeloma development similar to the human disease.