A genomic fragment containing the coding exons of the chicken lysozyme gene (also known as hen egg lysozyme, HEL) was linked to the ubiquitously-active mouse H2-Kb promoter and transmembrane sequence (which included the extracellular spacer sequence, transmembrane segment, and cytoplasmic tail). Fluorescence activated cell sorting (FACS) analysis of cells from spleen, lymph node, bone marrow, and thymus from mice carrying the transgene showed membrane expression of chicken lysozyme on these cells.