This invention relates to lymphotoxin-, a lymphocyte membrane type protein. This protein is found on the surface of a number of cells, including phorbol ester (PMA) stimulated T cell hybridoma II-23.D7 cells. This invention also relates to complexes formed between lymphotoxin- and other peptides such as lymphotoxin- and to complexes comprising multiple subunits of lymphotoxin-. These proteins and complexes are useful in holding LT- formed within the cell on the cell surface where the LT-/LT- complex may act as an inflammation regulating agent, a tumor growth inhibiting agent, a T cell inhibiting agent, a T cell activating agent, an autoimmune disease regulating agent, or an HIV inhibiting agent. Furthermore, the antitumor activity of the LT-/LT- complex may be delivered to tumor cells by tumor infiltrating lymphocytes (TILs) transfected with the gene for LT-.