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In vitro incubation of isolated X. laevis oocytes with progesterone induces the specific labeling of proteins during maturation. They are detected as several discrete peaks with a double-labeling technique that involves the injection of [3H] leucine into hormone-treated and [14C] leucine into control cells. The peaks are separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Identical proteins are obtained with two other steroids that provoke maturation and with p-chloromercuribenzoate. The same progesterone-induced proteins are observed even if oocytes have been treated with actinomycin D or ethidium bromide or have been enucleated. Cycloheximide suppresses the labeling of proteins that are induced by progesterone, if administered either at the time of radioactive amino acid exposure or after prelabeling the oocytes to determine whether the hormone-induced peaks are due to compartmental changes of the proteins. A cytoplasmic fraction, obtained from maturing oocytes before GVBD, promotes maturation when injected into resting oocytes and therefore contains an MPF. After this injection, GVBD occurs earlier than during incubation with progesterone and is accompanied by the formation of the same proteins and of MPF, both suppressed by cycloheximide. The possibility that MPF is an induced protein is then discussed. It has been also found that there is a decrease in membrane permeability, as evidenced by decreased leucine uptake into proteins of oocytes incubated in radioactive amino acids and exposed to progesterone. The same decrease occurs after injection of MPF-containing cytoplasm into oocytes.

Leucocyte migration inhibition detected in vitro by the capillary tube technique (LMCT) has proved a useful tool for detection of tumor-specific cell-mediated hypersensitivity (TCMH) in man. Investigations in pateints with renal tumors are reported. It is shown that TCMH is a feature of hypernephroma in man, that the antigenic specificity is found in autologous as well as allogeneic tumor tissue and in fetal kidney tissue. The pattern of reactivity compared to postoperative survival and occurrence of metastases and postoperative clinical course shows a clear association between TCMH and tumor elimination. The capacity of hypernephroma patients to develop a cell-mediated immune response is generally not reduced. In allogeneic combinations, small noninvading tumors usually have a high antigenicity, whereas tumors with early dispersion show a low antigenicity. The development of TCMH and associated tumor elimination therefore may be depending preferably on the antigenicity of the tumor, less on the immune capacity of the tumor host.