Differentiation of memory T cells to virus plaque-forming cells and cytotoxic T lymphocytes

The aims of this study were to define the T-cell subpopulation(s) detected by the virus plaque assay, and particularly to determine whether the virus plaque assay could be used to enumerate cytotoxic T lymphocytes. In addition, studies were undertaken to ascertain whether cell proliferation was required for development of cytotoxic effector function and virus plaque formation by these subpopulations. The results of experiments with a secondary mouse mixed lymphocyte culture (MLC) model indicated that 70 percent of virus plaque-forming cells bore the Ly 1 phenotype and 30 percent the Ly 2,3 phenotype. Three lines of evidence suggested that cytotoxic T lymphocytes (CTL) can be detected by this assay: the fact that some virus plaque-forming cells (V-PFC) bear the same Ly phenotype as CTL; the use of an inhibitor of DNA synthesis indicated that proliferating cells could be eliminated with no effect on V-PFC production and cytotoxic activity of the Ly 2,3 cell population; and that infection of primed lymphocyteswith vesicular stomatitis virus before (MLC) stimulation eliminated cytotoxic activity. In primary MLC, development of V-PFC and CTL was completely abolished by cytosine arabinoside. In contrast, in secondary MLC, some CTL and V- PFC were generated by antigenic stimulation in the absence of proliferation. However, the development of both functions became progressively more susceptible to cytosine arabinoside as the time between primary immunization and in vitro boosting is increased. It is suggested that there may be a considerable disparity between the number of existing effector cells at any given time and the cytotoxic potential, i.e. the number of cells capable of being generated by antigenic stimulation.     

Induction of the EBV cycle in B-lymphocyte-derived lines is accompanied by increased natural killer (NK) sensitivity and the expression of EBV-related antigen(s) detected by the ADCC reaction

Human B-lymphocyte-derived lines were forced to enter the EBV-cycle by superinfection with the P3HR-l substrain of EBV or sodium butyrate treatment. The induced cells were used as targets for natural killing (NK) and EBV-specific, antibody-dependent cellular cytotoxicity (ADCC). Two Burkitt lymphoma lines, Raji and Daudi, and one normal adult derived lymphoblastoid cell line, NAD-7, were comparable in their ADCC-sensitivity after induction, but only the Burkitt lymphoma-derived lines showed a major increase in NK-sensitivity. The superinfection-induced membrane change, responsible for both NK and ADCC sensitivity, is an early function of the viral cycle, correlated with the appearance of early antigens (EA). Indirect evidence indicates that the NK and ADCC target sites are different but this problem requires further investigation. Sodium butyrate induced an increased NK sensitivity and EBV-related ADCC sensitivity in the Burkitt lymphoma-derived P3HR-l line. Lymphocyte effectors from different donors showed great differences in their NK and ADCC activity. Optimal ADCC could be demonstrated with effectors that were intermediate in their NK-activity.     

Prenatal ultrasound diagnosis of clubfoot

Five cases of congenital clubfoot diagnosed prenatally by ultrasound are reported. The incidence of clubfoot may be higher within an affected family and may be associated with other structural anomalies or chromosomal abnormalities. Identifying a clubfoot in utero should therefore alert the sonographer that other anomalies may be present and should lead to a detailed structural survey.     

Absence of a facilitory role for NK 1.1-positive donor cells in engraftment across a major histocompatibility barrier in mice

Ex vivo T cell depletion of donor marrow grafts in humans and mice has virtually eliminated severe graft-versus-host disease (GVHD). However, as a consequence of T cell depletion, sustained donor cell engraftment is likely compromised. Since the majority of T cell depletion techniques also deplete natural killer (NK) cells, we investigated the role of donor NK cells in engraftment and GVHD in a murine model. Using a monoclonal antibody directed against an NK-specific epitope, we have selectively depleted NK cells while preserving donor marrow T cells. In an established model of engraftment, selective NK depletion demonstrated that removal of donor NK cells did not impair the engraftment process under conditions in which donors and recipients are major histocompatibility complex-disparate. In contrast, recipients of anti-Thy 1.2 plus complement (C')-treated marrow grafts had a significantly higher incidence of either partial engraftment or graft rejection as compared with recipients of selective NK-depleted donor grafts or control grafts. In addition, we have observed that NK-specific depletion of donor marrow/splenocyte inocula does not alter the incidence of GVHD. Recipients of NK-depleted donor grafts developed lethal acute GVHD, whereas recipients of anti-Thy 1.2-depleted donor grafts did not (P less than 0.0001). Interestingly, NK 1.1-depleted donor graft recipients had a significantly increased mortality in comparison with control groups receiving C'-treated grafts (P = 0.04) or anti-Thy 1.2 plus C'-treated grafts (P less than 0.05). Thus, NK depletion may reduce immunosurveillance, thereby increasing the risk of posttransplant infection. We conclude from these results that donor NK cells play an insignificant role in engraftment as well as in the afferent phase of GVHD, but may be important in immunosurveillance when murine bone marrow is transplanted across the major histocompatibility barrier.