MHC class II molecules present antigen to CD4 T cells and co-stimulation binding of B7 to CD28 on the T cell leads to full activation of the naive T cell. Must Know: Feature Class I MHC Proteins Class II MHC Proteins Present antigen to CD4-positive cells No Yes Present antigen to CD8-positive cells Yes No Found on surface of all nucleated cells Yes No Composed of two peptides encoded in the HLA locus No Yes Composed of one peptide encoded in the HLA locus and a 2-beta 2 microglobulin Yes No Ref: Review of Medical Microbiology & Immunology, 12e, Chapter 62. Major Histocompatibility Complex & Transplantation.