A combined analytical-numerical study is presented for the diffusiophoretic motion of a finite chain of colloidal spheres in a gradient of an uncharged solute prescribed along their line of centers. The spheres may be made up from different materials and have arbitrary radii, and they are allowed to be unequally spaced. Also, the spheres can be either freely suspended in the fluid or connected by infinitesimally thin rods. The range of the interaction between the solute and the particle surfaces is assumed to be small compared to the radius of each particle and to the gap thickness between any two neighboring particles, but the polarization effect of the diffuse solute in the thin particle-solute interaction layers caused by the strong adsorption of the solute is incorporated. A slip velocity of the fluid and a normal flux of the solute at the outer edge of the diffuse layer are used as the boundary conditions for the fluid domain outside the thin diffuse layers. Through the use of a collocation technique along with these boundary conditions, a set of transport equations governing this problem is solved in the quasisteady limit and the particle interaction effects are computed for various cases. It is found that diffusiophoretic particles with the same surface properties will interact with one another, unlike the no-interaction results obtained in previous studies assuming that the diffuse layer is infinitesimally thin. The larger the polarization effect in the diffuse layer is, the stronger the particle interactions in diffusiophoresis are. Generally speaking, the particle interaction effects can be quite significant under appropriate conditions.