C. A. St. Hill

Immunological Responses in Pregnancy and Survival of Fetal Homograft

Immunological responses were studied in pregnant women and controls using as tests phytohaemagglutinin-induced lymphocyte transformation and the tuberculin reaction. Significantly reduced responses were found to both tests in the pregnant women. These results suggest that a reduction in T-cell activity during pregnancy may help protect the fetus from rejection by its mothers immunological mechanisms.

Depression of Cellular Immunity in Pregnancy due to a Serum Factor

Lymphocytes from pregnant women and non-pregnant individuals were cultured under the stimulus of phytohaemagglutinin in the presence of their own and heterologous (allogeneic) sera. The results indicate that heterologous sera have an inhibitory effect on the lymphocyte transformation rate and suggest that the inhibitory property is more powerful in pregnant and fetal sera. Conversely, the addition of heterologous non-pregnant sera to cultures of pregnant lymphocytes increases their transformation rate. These findings suggest that there is a serum inhibitor in pregnancy and this finding may be relevant to the survival of the fetal allograft.

The biochemistry of vitreous humour. A comparative study of the potassium, sodium and urate concentrations in the eyes at identifical time intervals after death

Analysis of the vitreous humour from an individuals eyes collected at the same time since death showed variation between the eyes in the concentration of potassium, sodium and/or urate. This previously unreported finding would limit the use of measuring these electrolytes in determining the time of death.

FETO-MATERNAL BIDIRECTIONAL MIXED LYMPHOCYTE REACTION AND SURVIVAL OF FETAL ALLOGRAFT

Maternal and fetal lymphocytes were tolerant of each other in the bidirectional mixed lymphocyte reaction. This seems to be the principal reason why the mother does not reject the fetal allograft. Tolerance between maternal and fetal cells must be largely due to a genetic mechanism, because the bidirectional mixed lymphocyte reaction between parents and older children was much reduced compared with that between randomly selected pairs of controls. This weak reaction disappeared when immunosuppressive agents were given to one member of the parent/child pair, whereas the mixed lymphocyte reaction between unrelated individuals was not abolished by similar immunosuppression. It is suggested that this genetic mechanism is distinct from the HLA system. Tolerance between maternal and fetal cells was not demonstrated in the unidirectional mixed lymphocyte reaction, suggesting that this tolerance requires the viability of the two cell populations.

The biochemical changes in pericardial fluid after death. An investigation of the relationship between the time since death and the rise or fall in electrolyte and enzyme concentrations and their possible usefulness in determining the time of death

This paper reports the biochemical changes that occur in pericardial fluid after death. Significant changes in relation to the time since death occurred in potassium, sodium, phosphate, protein and several commonly measured enzymes. The variation in individual results at similar times since death would limit the use of pericardial fluid biochemistry in determining the time of death.

New approach to organ transplantation based on the fetal allograft.

A new approach to organ transplantation that may be particularly applicable to kidney transplantation is suggested by analogy with the immunological mechanism responsible for the survival of the fetal allograft. The method concerns identifying donor-recipient tissue compatibility by use of the two-way mixed lymphocyte reaction (MLR), in which reacting cells from patients awaiting transplants are primed with phytohaemagglutinin (PHA) and stored. When a donor becomes available, these PHA-primed cells may then be tested against donor lymphocytes, possibly giving a result within 36 hours. Immunosuppressive agents occurring naturally in pregnancy, such as alpha-fetoprotein and chorionic gonadotrophin, may eventually replace standard immunosuppressive treatment with potentially toxic regimens in transplant recipients. If the results of the two-way MLR using PHA-primed cells are shown to be comparable to those of the standard two-way MLR graft survival may be successful in 80% of cases.