Impact of prenatal testing on maternal-fetal bonding: chorionic villus sampling versus amniocentesis.

The process of maternal-fetal attachment, considered vital for normal infant development, begins during pregnancy and can be affected by a number of external factors. In this study the impact of prenatal testing on maternal-fetal bonding was evaluated in 253 women undergoing either first-trimester chorionic villus sampling (n = 101) or second-trimester genetic amniocentesis (n = 152). The women were evaluated by means of a modification of the Cranley Maternal-Fetal Attachment Scale, administered before and after the results of the prenatal diagnostic testing were made known to them (mean gestational ages of 10.6 and 15.7 weeks for the chorionic villus sampling group and 16.5 and 21.1 weeks for the amniocentesis group). The results showed: (1) that maternal-fetal attachment begins as early as 10 weeks' gestation and increases significantly as the pregnancy progresses, (2) that maternal-fetal attachment increases significantly, once the results are known to be normal, for both groups (p less than 0.001), (3) that this increase occurs about 5 weeks earlier for patients with chorionic villus sampling in comparison to those undergoing amniocentesis (p less than 0.001). Thus, with regard to the process of maternal-fetal attachment, first-trimester chorionic villus sampling appears to be preferable to second-trimester amniocentesis.

Isolation of a T cell specific cDNA clone possibly involved in the T cell activation pathway.

A T cell specific cDNA clone, YT15, has been isolated using the technique of subtractive hybridization. This gene is expressed predominantly in thymocytes and encodes a newly identified intracytoplasmic protein specific for T cells, since neither the nucleotide sequence of the cDNA clone nor the deduced amino acid sequence has significant homology to sequences in the GenBank or NBRF databases. The level of transcription of this gene in human leukemic cell line, Jurkat, can be reduced by stimulation of the T cell receptor CD3 (TcR-T3) complex. In addition, the levels of these messages are also greatly enhanced in some TcR/T3 receptor mutants. These findings suggest that this gene product may be involved in a T cell activation pathway within the cell.

T cell receptors.

Over the past few decades, a solid body of evidence has been built up linking certain autoimmune diseases to the presence of specific major histocompatibility complex haplotypes. Major histocompatibility complex products are used by the immune system to distinguish non-self from self and are important in the recognition of foreign antigen by T cells. T cells play a number of roles in the initiation and control of the immune response, leading to the suggestion that T cells may be important in the genesis of these diseases. T cell recognition is mediated by a heterodimeric cell surface receptor, the T cell antigen receptor. A better understanding of the molecular biology of this receptor may shed some light on the cellular and molecular processes involved in the initiation and progression of these diseases.

A human T cell-specific cDNA clone (YT16) encodes a protein with extensive homology to a family of protein-tyrosine kinases.

We report here the isolation of a human T cell-specific cDNA clone (YT16) that encodes a protein with extensive homology to a family of transformation and proliferation-related protein-tyrosine kinases (PTK). The message size of YT16 is 2.2 kb and it encodes a protein of 507 amino acids with a mol. mass of 57,136 Daltons. The deduced protein sequence has an overall homology of about 50% to the viral oncogene products of src and yes. Around the PTK catalytic domain, the homologies increase to 70-80% between the deduced protein sequence of YT16 and those of the PTK viral oncogenes. Of special interest is the extensive homology between the deduced protein sequence of YT16 and that of a recently reported murine B and T lymphocyte-specific PTK, lskT. It is possible that YT16 either encodes the human homologue of this murine gene, or a protein with similar function(s) in T cells.

Genes encoding the T-cell antigen receptor.

The search for the elusive and controversial T-cell antigen receptor is over. It is now clear that gene complexes for both alpha and beta chains are distinct from those for immunoglobulin genes. They are, however, related to Ig genes as well as to other class I and class II major histocompatibility complex (MHC) gene products. Therefore, they belong to the immunoglobulin super gene family.

T cell receptor alpha chain genes are located on chromosome 14 at 14q11-14q12 in humans.

A cDNA clone encoding the alpha chain of the human T cell receptor was used in connection with somatic cell human-rodent hybrids to determine that the genes coding for the alpha chain are located on chromosome 14 in humans. In situ hybridization confirms this result and further localizes these genes to 14q11-14q12 on this chromosome. Since this region of chromosome has been shown to be nonrandomly involved in a number of T cell neoplasias, this assignment raises a number of interesting questions as to the possible involvement of the T cell receptor alpha chain genes in tumorigenesis.

Gene rearrangement in cells with natural killer activity and expression of the beta-chain of the T-cell antigen receptor.

The mammalian host defence system can be divided broadly into adaptive and non-adaptive immunity. Adaptive immunity is acquired and is mediated by B and T lymphocytes. Non-adaptive immunity is mediated in part by a small subclass of heterogeneous peripheral blood mononuclear cells. This population, termed null cells, consists of haematopoietic precursors and cells mediating natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC). NK cells are a class of non-adherent, non-phagocytic, rapidly cytotoxic lymphocytes which can efficiently lyse a wide variety of tumour cells, virally infected cells and immature cell types of normal origin. Despite the broad range of targets, only a limited number of specificities are thought to be involved in target-cell recognition. Morphologically, NK cells are large granular lymphocytes, but they have been shown to exhibit cell-surface markers characteristic of both T cells and monocytes, raising doubt over their lineage. The recent cloning of the beta-chain of the T-cell antigen receptor has now allowed us to investigate whether some NK cells are T-cell-related. We have examined rearrangement and expression of the beta-chain of the T-cell receptor in cloned murine NK cell lines and fresh murine NK cell populations, and our results support the hypothesis that a subpopulation of NK cells is related to T cells and provide basis for examining whether some NK activity is mediated by a small number of T-cell receptors.

The T cell receptor beta chain genes are located on chromosome 6 in mice and chromosome 7 in humans.

Homologous clones that encode the beta chain of the T cell antigen receptor have been isolated recently from both murine and human cDNA libraries. These cDNA clones have been used in connection with interspecies hybrid cell lines to determine that the murine T cell receptor gene is located on chromosome 6 and the human gene on chromosome 7. In situ hybridization confirms these data and further localizes these genes to band B of chromosome 6 in the mouse and bands 7p13-21 in the human genome. The organization of the T cell antigen receptor J beta gene segments and C beta genes appears to be conserved, since very few intraspecies polymorphisms of restriction fragment length have been detected in either mouse or human DNA.