It is suggested that recombinant
galectin 9 (rGal 9), produced in host
Escherichia coli, exhibits an
immune system-mediated action and a direct action on
tumor cells (i.e., activity of inducing the intercellular adhesion and
apoptosis of the
tumor cells), thereby potent in inducing the inhibition of
cancer metastasis and reduction. Moreover, the rGal 9 exerts no
efficacy on non-activated lymphocytes but can induce
apoptosis in activated T cells, in particular, CD4-positive T cells causing an excessive immune response. The rGal 9 has a further potent
apoptosis-inducing property on synovial cells participating in joint deformation in
rheumatism, etc. In the rGal 9, however, a link domain linking two CRDs is highly susceptible to
protease and, therefore, is very easily digestible with the
enzyme, thereby losing the above activities. Thus, there is a need for a more stabilized molecule in view of further studies. Modification of the link domain linking two CRDs in
galectin 9 provides a modified molecule having an elevated activity without any undesirable effects on the above activities.