ABSTRACT
This chapter reviews the literature and data on the tissue distribution of human Ia-like antigens and compares it with that of Ia-like antigens in other animal species. Analysis of the tissue distribution of human Ia-like antigens has been greatly facilitated by the development of monoclonal antibodies which have optimized immunofluorescence studies on frozen sections of tissues by eliminating background staining. The expression of Ia-like antigens on cells of the myeloid series is restricted to early stages of differentiation, as these antigens are found on the vast majority of myeloblasts and on a minor fraction of promyelocytes, but are not detectable on more mature granulocytes. Malignant transformation of cells may be associated with changes in the expression of Ia-like antigens. Epithelial cells of mammary glands which undergo malignant transformation may lose la-like antigens. The level of Ia-like antigens in body fluids is low and may increase in patients with chronic lymphocytic leukemia.
