Role of integrin β1-like protein in proliferation and differentiation of cultured stem cells from midgut of Heliothis virescens

Cultured midgut cells from Heliothis virescens larvae were incubated with anti-human integrin beta(1) made in rabbit and then passed over a column of magnetic beads bound to anti-rabbit IgG (MACS, Miltenyi Bergisch Gladbach, Germany). Cells bound to integrin beta(1) antibody also bound to the anti-rabbit IgG on the magnetic beads (MACS) and were retained in the column while it remained in the magnetic field. Non-bound cells were eluted at this time. They did not stain with anti-integrin antibody just after elution. Removing the column from the magnetic field allowed cells bound to the beads-integrin beta(1) antibody to be eluted. All of these cells stained with human anti-integrin beta(1) upon elution. Each cell fraction was cultured in medium for 3 days. During this time, the populations of cells tended to return to heterogeneous staining patterns characteristic of control populations. However, cells that did not stain immediately with anti-integrin beta(1) antibody exhibited double the rate of multiplication and 8 times more differentiation than the integrin-anti body positive cells that eluted later, as well as the non-treated control cells. In a second experiment, midgut cells were incubated for 4 days with various titers of human anti-integrin beta(1) to block surface integrin beta(1)-like reactive sites Stem cells blocked with anti-integrin, beta(1) antibody during incubation exhibited double the rate of differentiation than non-treated control cells and those showing anti-integrin beta(1)-positive stain upon elution.