Preliminary study on the effect of substrate size on cellular immunomodulations

It is well known that the adsorption behavior of lymphocytes on fiber materials is related to the fiber size. In our previous study, murine lymphocytes cultured on various sizes of fibers showed different interleukin 2 (IL-2) activity, and ultrafine fibers of 1.5 microns showed the highest value. Based upon those results and to further evaluate the effects of fibers of different sizes on the modulation of lymphocyte functions, Concanavalin A (Con A) was immobilized on the surface of fibers having different diameters, and murine lymphocytes were cultured on these fibers. Fiber size effects on the lymphocytes were evaluated in terms of IL-2 production and adhesion morphology. The Con A immobilized fibers could stimulate lymphocytes to levels as high as 70-80% of the maximal value induced by the Con A solution. Statistical differences in IL-2 production were not observed among the fiber sizes although as fibers decreased in size, the contact area of the lymphocytes with fibers became smaller. The results suggest that smaller diameter fibers with less contact to adherent lymphocytes can affect lymphocyte function to similar extents on larger diameter fibers and that ultrafine fibers might be useful substrates for immobilizing immunomodulators.