Natural cytotoxicity of NC-2+ cells against the growth and metastasis of WEHI-164 fibrosarcoma.

We have previously reported a new receptor (NC-2) for natural cytotoxicity (NC) on murine leucocytes, identified by monoclonal antibody D9 (mAb D9). Pretreatment of mouse spleen cells with different concentrations of mAb D9 in vitro blocked NC against WEHI-164, whereas natural killing (NK) activity against YAC-1 was unaffected. This paper reports the immune surveillance against the growth of WEHI-164 tumour cells in mice by NC-2(+) Cells. The kinetics of in vivo reduction in NC activity were investigated by treating BALB/c and (CBA × C57BL/6) F1 mice with a single injection of 40 µg of mAb D9 and monitoring splenic NC activity by (51) Cr-release assay at intervals from 24 h to 3 weeks. Control mice were injected with OKT8 irrelevant antibody. Results showed a significant (P < 0.05) reduction in splenic NC activity within 24 h which persisted for up to 1 week. Similar results were also obtained when (CBA × C57BL/6) F1 mice were employed (P<0.001). In vivo tumour studies were undertaken to investigate the role of NC-2(+) cells in surveillance against tumour growth and metastasis of the WEHI-164 fibrosarcoma. When syngeneic BALB/c mice were injected with 40 µg of mAb D9 and then challenged with 5 × 10(5) WEHI-164 cells, results showed significantly increased growth rate of the transplanted WEHI-164 fibrosarcoma and tumour nodules in the lungs of animals, when compared to control mice with normal NC activity. Our data support an innate surveillance in metastasis and growth of WEHI-164 fibrosarcoma in mice.

The localisation of intracellular immunoglobulin and alpha-1-antitrypsin by immunoelectron staining of post-osmicated, resin-embedded tissue.

An indirect immunoperoxidase method is described to demonstrate intracellular immunoglobulins and alpha-1-antitrypsin in semithin and ultrathin sections from human tissue. The tissue was primarily fixed in glutaraldehyde, post-osmicated and resin-embedded.

Ultrastructural demonstration of immunoglobulin in glutaraldehyde fixed resin embedded human tonsil by an indirect immunoperoxidase method.

A post-embedding method has been established for demonstrating intracellular immunoglobulin using an immunocytochemical technique on material which has been fixed to glutaraldehyde and resin embedded. This allows localisation at both a light and ultrastructural level with good preservation of tissue structure.

Castanospermine, an oligosaccharide processing inhibitor, reduces membrane expression of adhesion molecules and prolongs heart allograft survival in rats.

The inhibition of intracellular oligosaccharide processing is a new approach to immunosuppression in allotransplantation. The net effect of such inhibition is reduction in the membrane expression of certain glycoproteins. Hence cell-cell interaction in allorejection may be impaired in the presence of glycoprotein processing inhibitors because the expression of key ligand-receptor pairs of N-linked glycoproteins including adhesion molecules is inhibited. The aims of this study were to measure the immunosuppressive ability of castanospermine (CAST) in a rat heart allograft model, to measure its effect on membrane expression of adhesion molecules (LFA-1 alpha, LFA-1 beta, ICAM-1), class I and class II MHC antigens and on other T cell associated molecules (CD4, CD8, CD39, CD45, W3/13), to test its tolerogenic potential and its toxicity. Membrane expression of these molecules was measured by flow cytometry for single cells and by immunoperoxidase staining for the allograft. In grafted rats CAST significantly reduced the expression of LFA-1 alpha on lymphoid cells in the thymus, lymph node, spleen and heart allografts. ICAM-1 expression on endothelial cells of the allograft vasculature, class I and class II MHC expression on lymphoid cells in the thymus, class II MHC expression on lymphoid cells in the allograft; and CD4, CD8, CD45 and W3/13 expression on lymphoid cells in some organs. By contrast, in non-grafted rats CAST significantly upregulated expression of class I MHC and CD45 in the thymus, lymph node and spleen, ICAM-1 and CD4 on lymphoid cells in the spleen, but reduced expression of LFA-1 alpha on lymphoid cells in the thymus. It also prolonged rat heart allograft survival in a dose-dependent manner and with limited testing was relatively non-toxic. In conclusion, CAST is an immunosuppressive molecule which may work by downregulation of the ligand-receptor adhesion molecule pair, LFA-1 alpha-ICAM-1 although subtle downregulation of class I and II MHC, CD4 and CD8 molecules could also contribute to its immunosuppressive activity. Hence, both lymphocyte-endothelial cell binding and lymphocyte activation may be inhibited by CAST. This work suggests that CAST may hold significant potential as a transplant immunosuppressant probably as an adjuvant agent to inhibitors of interleukin 2 secretion.

An evaluation of peripheral blood platelet enumeration as a monitor of fertilization and early pregnancy.

This paper reports our data that confirm the existence of early pregnancy-associated thrombocytopenia (EPAT) in the mouse and illustrate that the phenomenon is independent of age, parity, and strain differences. This paper also provides evidence that the EPAT phenomenon is induced by a soluble factor (EPAT-factor) released by the fertilized ovum. EPAT-factor was produced in vitro by mouse embryos from the 1-cell stage to the expanded blastocyst stage. The human study involved a "blind" analysis of serum samples, collected from in vitro fertilization-treated patients, for the presence of thrombocytopenic activity. Results suggest that measurement of this thrombocytopenic activity might be useful as an index of embryo viability and might be clinically applicable for the monitoring of implantation success in in vitro fertilization programs.

Early pregnancy factor: its role in mammalian reproduction--research review.

An immunosuppressive early pregnancy factor associated with mammalian reproduction is currently attracting considerable interest. Research into its detection, site of production, distribution, immunosuppressive property, characterization, and application is in progress in a number of laboratories. This review aims to crystallize the current research findings and to identify significant areas for further investigation and application.

Validation of the rosette inhibition test for the detection of early pregnancy in women.

The authors validated use of the rosette inhibition test for the detection of early pregnancy factor (EPF) in human pregnancy, first by optimizing conditions for the assay, using known pregnant and nonpregnant sera, and second, by examining the performance of this assay in three clinical situations: a "blind" study involving coded first-trimester sera showed 80% correlation with pregnancy status; serial assay of EPF activity in sera collected from normal women attempting to conceive, correlated with human chorionic gonadotropin beta-subunit (beta-hCG) levels and pregnancy status; a longitudinal study of serial serum samples through two normal pregnancies showing the continued presence of EPF until the early third trimester in each case. It was concluded that with the rosette inhibition assay, consistent demonstration of a pregnancy-associated substance (EPF) could be obtained.

Early pregnancy factor as a monitor for fertilization in women wearing intrauterine devices.

Measurement of early pregnancy factor (EPF) by the rosette inhibition test was performed on serum samples from 14 women using intrauterine devices (IUDs). Serial blood samples taken during the luteal phase of 23 cycles demonstrated in six of the cycles a transient appearance of EPF during the 6- to 8-day period following ovulation. In contrast, no EPF activity was found in sera obtained from women in whom fertilization was prevented, either by sexual abstinence or tubal ligation. These observations support the postulate that the IUD functions by the prevention of implantation of the fertilized ovum, rather than by preventing fertilization.

Mechanistic studies of early pregnancy associated thrombocytopenia (EPAT) in the mouse.

The preimplantation period of uterine pregnancy is associated with the transient (first 4 days of gestation) expression of a state of early pregnancy-associated thrombocytopenia (EPAT), a phenomenon shown to be mediated by the embryo-derived EPAT factor, which presumably causes platelet activation and subsequent removal. We previously investigated the time course of production of EPAT factor in mouse embryo culture medium and found a correlation between the production of this factor and the in vivo platelet alterations in pregnant mice. The present paper supports the postulation that the EPAT factor and PAF-acether (a phospholipid platelet-activating factor) are related by providing data showing that PAF-acether may be responsible for the thrombocytopenia. Finally, data are presented to suggest that platelet activation, though not affecting the rate of ovulation, is important for successful ongoing pregnancy. Results suggest that the EPAT factor, produced by the fertilized egg, might act to signal uterine decidualization and/or modulate maternal immunological rejection of the implanting conceptus.

Anaerobic exercise causes transient changes in leukocyte subsets and IL-2R expression.

There is evidence that the stress of intense athletic competition and training depresses cellular immunity and predisposes athletes to increased infection. This paper reports changes in circulating leukocyte subsets of trained (group I: VO2max = 67.2 +/- 5.4 ml.kg-1min-1; age = 22.0 +/- 6.2 yr) and untrained (group II: VO2max = 55.0 +/- 4.9 ml.kg-1min-1; age = 21.4 +/- 2.0 yr) males following 1 min of bicycle ergometry at maximum effort. Significant post-exercise increases in concentrations of total leukocytes, monocytes, lymphocytes, CD3+, CD4+, CD8+ lymphocytes were observed in both groups (all P < 0.01). The CD4/CD8 ratio decreased significantly (P < 0.01) but the granulocyte concentration was not altered (P > 0.05). Despite groups I and II not differing in either peak power or total work performed during the exercise test (P > 0.05), group II had a significantly greater concentration and percentage of CD8+ lymphocytes immediately after exercise (P < 0.01). All of the early changes were transient, with normalization occurring within 1 h. Only trained subjects showed a significant decrease in the percentage of CD25+ lymphocytes following PHA stimulation of whole blood obtained 6 h post-exercise. Alterations in leukocyte subpopulations found in response to predominantly anaerobic exercise appear to be associated with a significant, but possibly transient, alteration in the mitogenic responsiveness of lymphocytes that is restricted to aerobically trained subjects.