The data presented confirm expression of the three galectins, gal-1, gal- 3 and gal-8, and provide cellular localization for each, which has not been reported so far for human invasive trophoblast cells. Interactions of glycoconjugates with endogenous lectins such as galectins, have been long proposed to participate in several reproductive processes including fertilization, blastocyst attachment, and implantation. Previous seminal studies that addressed the physiological significance of galectins for reproduction were conducted in mice with gene neutralization of gal-1 alone, or with gal-3. A long standing interest of this group has been the relevance of galectins for the invasive properties of normal and transformed trophoblast. Gal-1, gal-3, and gal-8 are expressed by the invasive extravillous trophoblast of the cell column and the immortalized invasive trophoblast cell line HTR-8/SVneo. Therefore, in the present investigation the issue of potential participation of gal-1 in human trophoblast cell invasion in vitro using cell models was examined. This approach was based on the availability of a unique anti-gal-1 antibody with function blocking characteristics demonstrated in other systems, as well as two molecular forms of biologically active recombinant human gal-1. In neurobiology, application of the same anti-gal-1 antibody with neutralizing activity LY2835219 strongly inhibited axonal regeneration of peripheral nerves after axotomy, both in vivo and in vitro. In order to use this antibody to block cell function of the trophoblast, it was initially tested for recognition of gal-1 at the previously described placental locations. It was found to recognize gal-1 at all sites and cell types as previously described, and also to bind to HTR-8/SVneo cells in culture. Therefore, it was concluded that the anti-gal-1 used here met the initial criteria for further use to block cell functions. Cell adhesion in general depends on the presence of membrane constituents able to bind stably to different surfaces. Since we have previously demonstrated that lactose, an inhibitory sugar for the lectin-type interaction of galectins, reduced invasion by the extravillous trophoblast HTR-8/SVneo cell line, its possible effect on cell adhesion was examined here. We hypothesized that endogenous gal-1 could participate in cell adhesion by binding cell membrane glycoproteins and/or ECM proteins Everolimus produced by cells or present in the culture vessel coating. This was confirmed by our finding that lactose inhibited HTR-8/SVneo cell adhesion to plastic and collagen type I. Antibody that binds this gal-1 could in turn interfere with the efficiency of cell adhesion. In the presence of anti-gal-1 antibody, cell adhesion was increased to both plastic and ECM protein coated surfaces. This was an intriguing finding which probably reflects complex interactions between endogenous gal-1, its trophoblast ligands, and the antibody introduced into the test system. There is a possibility that the antibody reinforces existing complexes and adhesion, and/or further cross links membrane and ECM bound gal-1.