Oligoclonality of Vdelta1 and Vdelta2 cells in human peripheral blood mononuclear cells: TCR selection is not altered by stimulation with gram-negative bacteria.

Despite the enormous potential repertoire of gammadelta T cells, there are several observations which suggest that the expressed gammadelta repertoire in the periphery of normal individuals is often quite restricted. To assess selective expansions among gammadelta T cells from both adult and newborn blood samples, PBMC from 12 normal adults and cord blood from 15 normal newborns were analyzed for TCRDV1 and TCRDV2 junctional diversity by CDR3 size spectratyping and single-strand conformational polymorphism. Although TCRBV usage showed extensive heterogeneity in adults and newborns, both populations often showed CDR3 region restriction for TCRDV1 and TCRDV2. Analysis of the CDR3 spectratype patterns of newborn twins suggested that clonal selection for TCRDV is independent of genetic background. The possible role of Gram-negative bacteria in driving selective responsiveness of gammadelta T cells in PBMCs from adults was examined by in vitro stimulation with Escherichia coli and Pseudomonas aeruginosa. Donors whose TCRDV repertoire was highly clonal in the unstimulated blood cells showed the same predominant clones among the bacteria-stimulated cultures. In individuals whose gammadelta T cells were less restricted, in vitro stimulation did not select for clonality; rather, the TCRDV repertoires were similar before and after bacterial stimulation. Together, these data indicate that gammadelta T cells are often clonally restricted in adults as well as in newborns and suggest that the prominent stimulatory activity of Gram-negative bacteria does not by itself account for the restriction or diversity of the gammadelta T cell repertoire.

Fetal origin of amniotic fluid polymorphonuclear leukocytes.

OBJECTIVE: Although polymorphonuclear leukocytes are the inflammatory cells most frequently recovered from the amniotic cavity in cases of suspected intrauterine infection, the source of these cells has not been definitively determined. We took advantage of the gender difference between the mother and her male fetus, and we report four cases in which amniotic fluid polymorphonuclear leukocytes were identified as fetal by fluorescence in situ hybridization with probes specific for X and Y chromosomes. Fetal membranes were intact at the time amniotic fluid was obtained in all cases. STUDY DESIGN: Amniotic fluid was obtained from women with male fetuses in premature labor with clinical or laboratory evidence of infection. Cytospin preparations of amniotic fluid samples with polymorphonuclear leukocytes were prepared and sequentially stained with fluorescent reagents. To determine which cells were polymorphonuclear leukocytes, all replicate samples were stained with the fluorescent nuclear stain 4'-6-diamidino-2-phenyl-indole. This allowed definition of the characteristic multilobed polymorphonuclear leukocytes nuclear morphologic features. The sample was then probed with a rhodamine-labeled probe specific for the X chromosome and a fluorescein-labeled probe specific for the Y chromosome to assess whether the polymorphonuclear leukocytes were male or female. RESULTS: Ninety percent to 99% of polymorphonuclear leukocytes identified by normal multiple lobed nuclear morphologic study on 4'-6-diamidino-2-phenyl-indole staining had an X and Y chromosome and were therefore fetal cells. CONCLUSIONS: These data demonstrate a fetal response during intraamniotic infection. Further investigation of the roles for maternal and fetal polymorphonuclear leukocytes in chorioamnionitis may provide valuable information about the critical interaction of the two immune responses in this setting.

Prenatal genetic diagnosis by isolation and analysis of fetal cells circulating in maternal blood.

In recent years, considerable progress has been achieved in the genetic analysis of fetal cells isolated from maternal blood. The goal of clinical diagnosis of either fetal chromosome abnormality or Mendelian DNA mutation has already been realized in an ever-increasing number of cases. The remaining challenges involve increasing the yield and visual identification of fetal cells while decreasing the remaining numbers of maternal cells. It is presently unknown whether the frequency of fetal cells in maternal blood differs in cytogenetically abnormal pregnancies as compared with normal pregnancies. Although fetal cells in maternal blood have a practical role in prenatal diagnosis, their very existence and persistence in the mother raise many new questions regarding maternal-fetal interaction.

Should all pregnant patients be offered prenatal diagnosis regardless of age?

OBJECTIVE: To assess the acceptance of prenatal genetic diagnosis by patients younger than 35 years old who are therefore not yet at great risk for non-disjunction trisomies based on maternal age. METHODS: The patients were counseled regarding the following: 1) the age-related risk of chromosomal abnormalities, 2) the procedure-related risk of fetal loss, 3) clinical implications of chromosomal abnormalities, 4) the need for complete counseling by a certified genetic counselor, and 5) the patient expense of $600-1200 if third-party reimbursement was not available. Patients were recruited from the private practice of the senior author at the New York Hospital--Cornell Medical Center. Five hundred ninety-one patients were offered prenatal genetic diagnosis. The outcome measure was the patient's decision to undergo prenatal diagnosis even though the risk of a non-disjunction trisomy was expected to be low based on maternal age. Amniocentesis was performed in 128 patients and chorionic villus sampling in five. RESULTS: One hundred thirty-three patients (22.5%) chose prenatal diagnosis. Karyotype was obtained in 131 procedures, but two were unsuccessful. One of the 131 karyotypes was abnormal and the patient chose to terminate the pregnancy. CONCLUSIONS: The data showed the following: 1) Inappropriate influence of patients by the health provider was not evident; 2) routine offering of genetic diagnosis enhanced the autonomy of pregnant women; 3) the potential increase in the loss of pregnancies that accompanies this practice is ethically justified; and 4) there are no compelling cost-benefit objections to such a practice.