Protein composition of human uterine fluid.

Polyacrylamide gel electrophoresis of uterine washings and the corresponding serum from 35 patients revealed the presence of at least four characteristic uterine proteins and large amounts of the serum proteins, albumin and transferrin. The appearance of these characteristic proteins was studied during specific phases of the menstrual cycle. At lease one of the four uterine proteins was observed in postovulatory samples only, with a maximum frequency of occurrence during the midsecretory phase. In contrast, one of these proteins predominated in preovulatory uterine washings while another appeared randomly throughout the menstrual cycle. Substantial variations in protein patterns were observed in patients sampled during different menstrual cycles. The presence of the major antigenic components of serum in uterine washings was confirmed; however, immunochemical demonstration of the existence of uterine-specific antigens was unsuccessful.