Cord serum inhibits allogeneic mixed lymphocyte reaction and stimulates lymphokine production

The proliferative responses of lymphocytes from foetal calves and adult cattle

This paper describes the proliferative responses of prescapular lymph lymphocytes and peripheral blood lymphocytes of foetal calves compared with cells of similar origin from adult cattle. Lymph lymphocytes were collected continuously by means of cannulation of efferent lymphatic ducts of the prescapular lymph node of foetal calves and adult cattle. Peripheral blood lymphocytes were collected from the foetus by means of cannulation of superficial veins of the foetus or of the umbilical vessels and from the jugular vein of adults. Foetal lymphocytes in one-way mixed lymphocyte culture stimulated and responded as well as adult lymphocytes. Foetal cells stimulated and responded more to cells from unrelated animals than to cells from their dam. Lymph lymphocytes from foetal calves between 188 and 253 days of gestation proliferated as well as adult lymphocytes and at a high level after stimulation with concanavalin A, phytohaemagglutinin and pokeweed mitogen. Response to stimulation with lipopolysaccharide, soybean agglutinin and wheat-germ agglutinin was variable but generally low and within the same range recorded by adult cells. Proliferation by foetal and adult whole-blood cultures was on occasions as high as that recorded by separated lymphocytes, even though fewer lymphocytes were initially present in the whole-blood cultures. Foetal lymph lymphocytes exhibited lower proliferative responses in autologous lymph plasma than in foetal calf serum or pooled foetal lymph plasma. There was no consistent depression of proliferation by culture medium supplements from pregnant animals. Rabbit serum consistently abrogated responses. Fetuin at final concentrations of greater than 2.5 mg/ml significantly depressed proliferation in foetal and adult lymphocytes from efferent lymph and peripheral blood.

Placental isoferritin as a marker of early abortion in pregnancies induced by in vitro fertilization

The relatively high rate of early pregnancy loss in artificial reproductive technology-induced conceptions has driven researchers to seek for an efficient diagnostic tool for estimating the gestational risk in these cases. Monitoring early gestation normalcy using serial beta-human chorionic gonadotrophin (beta hCG) measurements requires several days before diagnosis can be established. The objective of this study was to determine whether placental isoferritin (PLF) can be used as a predictive marker of normal pregnancy development during early stages of in vitro fertilization (IVF)-induced pregnancy. Ninety-three consecutive IVF cycles were investigated. Blood samples for PLF (enzyme linked immunosorbent assay; ELISA) and beta hCG (radio-immunoassay; RIA) determination were obtained from all women on days 11, 13 and 15 following embryo transfer. Placental isoferritin was detectable in the serum 11 days after embryo transfer in IVF conception cycles. These levels were significantly higher in normally developing pregnancies (n = 18) than in cases which eventually aborted spontaneously (n = 9) during the first trimester (mean +/- s.d.; 33 +/- 28 U/mL as compared with 1 +/- 2 U/mL; P = 0.0004; Wilcoxon test; sensitivity 94.5 per cent, specificity 88.9 per cent, positive predictive value 89.9 per cent, negative predictive value 94.5 per cent). Moreover, in those patients who later aborted, lower than normal PLF levels were detected long before the decline in beta hCG titres was evident. Considering its suppressor activity, it is expected that PLF levels would be high at the initiation of normal pregnancy. This may explain the present finding of low PLF levels in abnormally developing IVF-induced pregnancies. These preliminary data suggest that PLF can be used as a sensitive marker for detecting those cases destined to abort at a very early stage. However, further studies are still required on spontaneous conceptions, before this test can be recommended for routine clinical application.

IL-2 receptor expression and function on human cord blood mononuclear cells following PHA and anti-CD3 antibody stimulation

Interleukin-2 receptors (IL-2R) on mononuclear cells from human umbilical cord blood were investigated after stimulation by phytohemagglutinin (PHA) and anti-CD3 antibody. The proportion of cells expressing the Tac antigen (IL-2R alpha, p55) did not differ from that for adult mononuclear cells. However, the levels of high affinity IL-2R (H-IL-2R) and low affinity IL-2R (L-IL-2R) present on the PHA blasts of cord blood cells were shown to be twice and three times, respectively, that of adults by interleukin-2 (IL-2) binding assay. The level of low affinity IL-2R in the cord blood cells was approximately double that of adult cells after activation by anti-CD3 antibody, but no difference was observed in the levels of high affinity IL-2R. Functional investigation of IL-2R revealed that the amount of internalized IL-2 in PHA-stimulated cord blood mononuclear cells was twice that in adult mononuclear cells but there were no differences between them in the time course of internalization and degradation. Although there were significant numbers of H-IL-2R in premature (25 and 28 weeks) infants following PHA stimulation, there were markedly fewer following anti-CD3 stimulation. Prematurity of the T-cell activation system through the CD3 pathway at this stage is therefore indicated.

The interleukin 2 gene is expressed in the syncytiotrophoblast of the human placenta

The lymphokine interleukin 2 is an important immune system regulatory glycopolypeptide. It is produced by antigen- or mitogen-stimulated T lymphocytes and is required for the proliferation or clonal expansion of activated T lymphocytes. In this report, it is demonstrated by RNA transfer blot hybridization that the poly(A)+ RNA population of the human placenta contains a 0.85-kilobase RNA transcript that specifically hybridizes to a human interleukin 2 cDNA probe. By using hybridization histochemistry in situ, it is further shown that interleukin 2 RNA transcripts are localized, primarily, to the syncytial (syncytiotrophoblast) layer of the human placenta. Possible roles for syncytiotrophoblast-produced interleukin 2 are suggested and discussed.

Interleukin-2 production by human fetal lymphocytes

IL-2 production by PHA-stimulated human lymphocytes in umbilical blood was studied ontogenetically. Lymphocytes from the 16-week-old fetus produced appreciable amounts of interleukin-2 (IL-2). In 16- to 36-week-old fetuses the IL-2 production rate was found to be significantly higher than that in adults. When signal transduction, which is mediated by high affinity IL-2 receptors (IL-2R), was studied after adding exogenous IL-2 to PHA-blast lymphocytes, the response of the 24-week-old fetus was similar to that of adults. These results indicate that the attainment of IL-2 production and the function of IL-2 receptors are completed at a relatively early stage of fetal development.