Summary and Conclusions
During the course of some experiments in serum sickness, it was observed that the skin seemed to possess an unusual capacity for sensitization to horse serum, this sensitization being accompanied by the production of anaphylactic antibodies, and these experiments suggesting the possibility that the skin may act as an important immunological organ. Numerous clinical observations bear out the close relationship existing between the skin and processes of immunity in infectious and allergic diseases. These have been further substantiated by many experimental contributions reported in the past few years in the foreign literature, which appear to indicate not only that the skin may have the power to form antibodies, but that such antibodies may be specific and that the ability to form such antibodies resides specifically in the skin. Our own experiments do not bear out this latter view, at least for antibacterial antibodies, for from a comparison of the antibody response after intradermal, subcutaneous, intramuscular and intravenous injection of mixed typhoid vaccine, both in the human and in the lower animals, it would appear that though it is possible that the skin participates actively in antibody production, it does not carry out this function exclusively in respect to other tissues or organs. The marked antibody response particularly after local injection can be best explained upon the basis of a local tissue stimulation of the cells of the reticulo-endothelial system, these cells being particularly abundant in the skin. That the active antibody response after intradermal injection may be due in part to a slower abosrption of the antigen is entirely possible, although this process may in turn allow for local fixation of a greater amount of antigen and thus greater local stimulation of antibody.
The conception of the skin as an important immunological organ explains in part the satisfactory results of those nonspecific mechanical therapeutic measures employing the skin surface for stimulation, and suggests the possibility of utilizing the skin, therapeutically, for measures of specific active immunization in infectious and allergic diseases. It also substantiates the rationale of the various measures of cutano-therapy advised by the French and Germans, and our own satisfactory experience with typhoid vaccine used intradermally is further evidence of the efficacy of such methods. These could well be extended to other bacteria, particularly such skin-affecting organisms as the pyogenic cocci, with good results.