CD1d-restricted immunoglobulin G formation to GPI-anchored antigens mediated by NKT cells

Immunoglobulin G (IgG) responses require major histocompatibility complex ( MHC)-restricted recognition of peptide fragments by conventional CD4(+) hel per T cells. Immunoglobulin G responses to glycosylphosphatidylinositol (GP I)-anchored protein antigens, however, were found to be regulated in part t hrough CD1d-restricted recognition of the GPI moiety by thymus-dependent, i nterleukin-4-producing CD4(+), natural killer cell antigen 1.1 [(NK1.1)(+)] helper T cells. The CD1-NKT cell pathway regulated immunogobulin G respons es to the GPI-anchored surface antigens of Plasmodium and Trypanosoma and m ay be a general mechanism for rapid, MHC-unrestricted antibody responses to diverse pathogens.