Mice homozygous for the Cd1tm1Gru targeted mutation are deficient in both the Cd1d1 and Cd1d2 genes (CD1.1, CD1.2). Homozygous mutant mice lack the normal natural killer cell-like T cell subset. However, type 2 T helper cell (TH2) response is normal, demonstrating that this T cell subset is not required for TH2 response, as previously believed. The Jackson Laboratory 2024, used with permission.