The skin of atopic patients contains specific reaginic antibodies in all epidermal cells, in unchallenged as well as antigen-challenged areas. The reagins are also present in the epithelial cells of sebaceous glands, sweat glands, hair follicles and also in macrophages and pericytes. Judged by staining characteristics, their immunologic reaction in tissues with antigen is identical with that of rabbit antibodies.
Comparison of tissues stained with conjugated reagins and conjugated anti-human globulin antibodies demonstrates the close relationship of reagins and globulins.
In antigen-challenged tissues the macrophages and pericytes become enlarged and stain more intensely with toluidine blue. No such changes in morphology or staining are present in histamine-tested or unchallenged atopic tissues.