Rosette inhibition test: A multicentre investigation of early pregnancy factor in humans

The rosette inhibition test for the detection of early pregnancy factor is described in detail. The extended methodology presented here represents the cumulative experience of three independent laboratories. Special reference is made to the effect on the assay of varying the conditions of rosette formation between lymphocytes and sheep red blood cells. Antilymphocyte sera prepared for use in the rosette inhibition test fell into three catagories: (i) with no rosette inhibiting activity, (ii) with rosette inhibiting activity which is not affected by the presence of EPF, and (iii) rosette inhibiting activity which is significantly increased in the presence of EPF. To date, this third reaction has been found to be a specific indication of the presence in serum of early pregnancy factor.     

The B-L (Ia-like) antigens of the chicken. Lymphocyte plasma membrane distribution and tissue localization

Specific antisera reacting with B-L (Ia-like) antigens were prepared by reciprocal immunization of animals from the congeneic lines CB and CC. The resulting antisera were tested either in direct or indirect immunofluorescence tests and stained 10-16% of peripheral blood cells (PBL). Of the B-L+ cells, 90% were B cells and 8% were T cells. After in vitro stimulation of PBL with ConA, 58% were B-L+ and 91% of these were T cells. B and T cells were defined by means of rabbit antisera raised against bursa and thymus cells made specific by absorption with the relevant tissues. Antigens determined by anti-B-L antisera, rabbit anti-bursa (ABS) and rabbit anti-thymus (ATS) sera showed an independent distribution on the membrane of PBL. The tissue distribution of B-L+ cells, defined by means of allo-antisera and monoclonal antibodies, was studied by direct and indirect immunofluorescence on sections of skin, liver, kidney and brain. In all organs, in addition to B cells and a small number of, presumably activated, T cells, macrophages and dendritic cells were positive. Notably, glia cells in the brain were also shown to express B-L antigen.     

An inhibitor of lymphocyte proliferation and lymphokine production released by unstimulated foetal monocytes.

Supernatants obtained from 3-day cultures of cord blood monocytes inhibited normal lymphocyte activation by either PHA or in a two-way MLC. Both lymphocyte transformation and lymphokine production was significantly inhibited by these supernatants but not by those derived from adult mononuclear cell cultures. The inhibitory material produced by foetal monocytes was dialysable and was non-cytotoxic to target cells. It is postulated that this factor contributes to the depressed maternal cell-mediated immune response observed in pregnancy.