Lymphokine killing activity (LAK) is a form of MHC-unrestricted tumor cell killing, induced by high dose IL-2 exposure from various lymphoid populations. Although it is well established that CD16+CD56+NK cells are one major source of blood-derived LAK precursors, subpopulations of other blood and tissue-derived lymphoid cells, are also recognized as a source of MHC-unrestricted killers (for example CD3+ gammadelta+ subclasse). This LAK lytic activity, as well as the associated secondary cytokines known to be active in various inflammatory reactions (arthritis, graft rejection, multiple sclerosis, thyroiditis, and others), may be useful for immunotherapy of cancer patients. Using human PBL and designated subclasses as the source of responsive cells, this grant aims to elucidate both the direct, and indirect, responses to IL-2 with respect to secondary cytokine regulation during development of oncolytic activity. Comparisons of whole PBL and major PBL subpopulations will be used to address differential responsiveness to, and differential expression of, secondary cytokines. Specific regulation of the identified secondary factor(s) will then be explored to determine whether they are obligatory or ancillary to LAK development, suing both serologic (monoclonal antibodies) and molecular methodology (antisense oligonucleotide). We will initially focus on TNF- alpha and TNF-beta, followed by the IL-1s, IL-6, IL-7, IFN-gamma, CLMF (IL- 12)?, and later possibly others. Because a commonality of the diverse LAK precursor cell types appears to be the intermediate affinity IL-2 receptor (known as the beta chain or P70-75), our experimental plan incorporates the elucidation of cytokine regulation of p75 expression (using mAbs and Scatchard analysis) and function (LAK activation). In parallel, the cytokine-dependent expression of the IL-2 receptor alpha-chain (p55) and the TNF receptors on lymphocytes (using utr and htr mABs) will be assessed to test more fully these cytokine-mediated regulatory circuits. These studies will provide a more comprehensive understanding of the cytokine regulation, heterogeneity, and possible plasticity of the MHC unrestricted tumor killing system. Such knowledge will improve our ability to regulate the inflammatory processes during the various diseases mentioned above.
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