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Four of ten patients with pemphigus foliaceus were found to have antibodies reacting specifically with antigens present only in the subcorneal (SC) intercellular substance of the epidermis. Similar SC intercellular antibodies were found in only one of 709 control patients, including 73 patients with other forms of pemphigus, 68 with other bullous diseases, and 569 with miscellaneous dermatoses. These antibodies were distinct from those normally found in pemphigus vulgaris that react with intercellular antigens all layers of the epidermis. The anatomical location of the antigens reacting with SC intercellular antibodies corresponds to that of the earliest lesion seen in pemphigus foliaceus, and suggests that this form of pemphigus may be associated with distinctive antibodies.

Antibodies against the cytoplasm of normal human epidermal cells were found in 4 of 23 (17%) normal persons, 12 of 57 (21%) patients with various dermatoses, 11 of 34 (32%) patients with malignant tumors, and 3 of 11 (27%) patients with malignant melanoma. These antibodies react against several different cytoplasmic antigens, some of which appear to be tissue- and species-specific, while others may also be present in heterologous stratified epithelial or smooth muscle cells.

The binding of antigen to cells with antibody on their surface has been studied in a model system consisting of murine myeloma cells (MOPC 315) and DNP conjugates. Specific binding occurred between the DNP groups of DNP conjugates and cell surface immunoglobulin. Using this model, the binding affinities of multivalent and univalent DNP conjugates were measured directly by equilibrium-binding techniques and indirectly by displacement of bound conjugate with univalent hapten. With both approaches the multivalent conjugate was shown to bind to cells with an avidity 100–300 fold greater than the univalent hapten. Nonspecific binding of unrelated protein and repeated washing of cells was found to markedly dedecrease the specific binding of univalent conjugates, presumably because the relatively weak bonds dissociate readily.

Rabbits were immunized to two antigens and 18–55 days later exchange transfusion was performed using blood of rabbits immunized to one antigen only. By this means, serum antibody levels to one antigen were reduced 50–84% while maintaining serum antibody levels to the second antigen. After exchange, serum antibody levels of the removed antibody rose rapidly for 24–48 hr and then more slowly, reaching peak titers an average of 8 days later. The peak titer was 48–222% higher than the preexchange titer. The specificity of this rebound excluded as a cause nonspecific changes in Ig levels. Passive administration of antibody to a third antigen 4–7 days before the exchange indicated that re-equilibration of preformed antibody was not a major factor in the rebound. A change in the ratio of IgM to IgG antibodies as a cause of an increased neutralization titer in the postexchange sera was also excluded. It was therefore suggested that a change in the rate of antibody formation had occurred, although other changes in the quality of serum antibody were not excluded.