Methods for selectively stimulating proliferation of T cells

A method for stimulating a population of CD8.sup.+ T cell to proliferate, comprising

• a) contacting a population of T cells with
• (1) a first agent which stimulates a TCR/CD3 complex-associated signal in the T cells;
• and
• (2) a second agent which stimulates a CD9 antigen on the surface of the T cells.

A method for stimulating a population of CD8.sup.+ T cells to proliferate, comprising:

• a) obtaining peripheral blood leukocytes from an individual;
• b) isolating a population of CD8.sup.+ T cells from the peripheral blood leukocytes by negative selection with a combination of antibodies directed to surface markers unique to the cells negatively selected;
• c) contacting the population of CD8.sup.+ T cells with an anti-CD3 antibody immobilized on a solid phase and a ligand which binds a CD9 antigen present on activated T cells, under conditions appropriate for stimulating proliferation of the T cells;
• d) separating the anti-CD3 antibody from the T cells and the ligand;
• e) monitoring proliferation of the T cells in response to continuing exposure to the ligand by examining cell size;
• and
• f) restimulating the T cells with the anti-CD3 antibody and the ligand when T cell size has decreased to induce further proliferation of the T cells.