OBJECTIVES: I. Determine the effect of nonmyeloablative chemotherapy followed by allogeneic peripheral blood stem cell transplantation on hematopoietic recovery in patients with hematologic malignancies. II. Determine the toxicities of this regimen in these patients. III. Determine the frequency of mixed hematopoietic chimerism in these patients after this therapy. IV. Determine the efficacy and toxicity of donor leukocyte infusions at relapse in these patients. V. Determine the response rates and survival of these patients after this therapy. VI. Determine the immune reconstitution of patients undergoing this therapy.