The reaction between normal serum and hyaluronidase has been studied in vitro and under in vivo conditions in skin. Using in vitro conditions of incubation, serum exhibits antihyaluronidase activity as measured by assay of hyaluronidase spreading activity in skin. This confirms the work of others, who have previously described the serum inhibitory factor using other tests of hyaluronidase activity. When, however, hyaluronidase and setum are allowed to incubate in skin under in vivo conditions, no inhibitory influence of serum upon hyaluronidase spreading activity is evident. This latter finding has been taken to indicate that the environmental conditions in skin are unfavorable for the inhibitory reaction of serum upon hyaluronidase. The disparity between the in vivo and in vitro effectiveness of serum, and the significance of the serum factor as a defense mechanism against invasive processes, have been briefly discussed.

This content is only available as a PDF.