Local Active Suppression by Suppressor Cells in the Decidua: A Review

ABSTRACT: The immunological survival of the antigen-bearing mammalian feto-placental unit is determined by the functional properties of the tissues at the feto-maternal interface. Antigen-specific systemic suppressor mechanisms such as suppressor T cells and non-antigen-specific suppressive serum factors appear not to play a major role in protection of the fetus. A novel type of non-MHC specific suppressor cell accumulates locally in the decidua of successfully allopregnant mice. This decidua-associated suppressor is a small lymphocytic cell possessing cytoplasmic granules, lacks T cell markers, and is deficient in number and activity at the implantation sites of viable xenogeneic Mus caroli embryos gestating in the uterus of Mus musculus animals at the time that maternal lymphoid cells begin to infiltrate the xenoembryos. These Mus caroli embryos subsequently resorb. Further experimental studies suggest that the trophoblast cells associated with successful pregnancy recruit bone-marrow derived maternal non-T suppressor cells to the decidua and thus, by an indirect mechanism, may act to protect the fetus from effector cells of the mother's immune system.     

OESTROGEN STIMULATED NEUROPHYSIN IN PREGNANCY AND LACTATION

Serum concentrations of oestrogen stimulated neurophysin (ESN) were measured throughout pregnancy in thirty-one women and until 6 weeks post-partum in a further twenty-three. During pregnancy ESN rose progressively and values during labour were similar to those immediately before delivery. There were significant correlations (P < 0–05) between serum ESN and oestradiol values measured in samples from four patients. After delivery the concentration of ESN fell rapidly to the range for non-pregnant women by 5 days post-partum, whether the mothers lactated or not, and remained fairly constant for the next 6 weeks. Bromocriptine or metoclopramide, drugs which affect prolactin secretion, were without effect on ESN values. At 8 days post-partum in sixteen of the eighteen patients studied there was an increase in ESN concentration 30 min after suckling commenced. At 6 weeks similar changes occurred in five of ten subjects studied. In contrast, at 8 days there was no significant change in ESN in four mothers who bottle fed their babies over the 90 min studied. The relationship between ESN and hormonal changes during pregnancy and lactation is discussed in the light of these results.     

HYPOTHALAMIC HORMONE INTERACTION IN ACROMEGALY

The growth hormone response to the administration of the currently available synthetic hypothalamic hormones was assessed in eleven patients with acromegaly. Eight of them showed a positive GH response to thyrotrophin releasing hormone and three showed no response. The GH response to TRH was shown to be unrelated to the thyrotrophin response to TRH. The GH response to TRH was inhibited by the administration of growth hormone release inhibiting hormone. Luteinizing hormone/follicle stimulating hormone releasing hormone (LHRH) caused a positive GH response in four patients, but this was trivial in three. The TRH mediated GH release in acromegaly is not mediated via TSH and appears to be attributable to loss of specificity of the receptor sites on the somatotroph to the hypothalamic hormones.     

Precipitins to dietary proteins in atopic eczema

Precipitating antibodies to foods have been assayed in three groups of patients with atopy. Forty-five per cent of patients with atopic eczema and IgE-mediated food allergy had precipitins to foods in their serum compared with only 15% of patients with atopic eczema without evidence of food allergy, and 16% of patients with atopic asthma and/or rhinitis. It is likely that this results from increased intestinal permeability in the group with eczema and food allergy.