Homozygous (CD1-deficient) mice are viable and fertile, with no protein expression from the targeted locus observed on antigen presenting cells (APC) by FACS analysis. Natural killer T (NKT) cells are restricted by MHC class I-like CD1 molecules expressed on APC, and because the CD1 molecule is also required for the development of NKT cells, these CD1-deficient mice selectively lack NKT cells. Because activated NKT cells normally produce interleukin-4 (IL-4), interferon-gamma, granulocyte-macrophage colony-stimulating factor, IL-2 and TNF-alpha, CD1-deficient mice may exhibit abnormal immune responses dependent upon such cytokines/chemokines. These CD1-deficient mice may be useful in studying NKT cell immunology; including Th1- and Th2-responses, antiviral and antitumor responses, asthma, various inflammatory responses, autoimmunity and peripheral tolerance.
