Comparative flow cytometry-based immunophenotyping analysis of peripheral blood leukocytes before and after fixation with paraformaldehyde.

Flow cytometry based immunophenotyping provides prime insight into cellular population composition and characteristics, and is widely used in basic and clinical research. Challenges in processing peripheral blood samples in a timely manner necessitate protocol adaptations and utilization of fixatives. Fixation, however, may introduce artifacts to the flow cytometry readout. We performed a comparative flow cytometry immunophenotyping analysis of 13 immune cell populations in the whole blood using a staining protocol with and without fixation step. Freshly procured human peripheral blood samples were stained with a panel of 33 fluorochrome-conjugated antibodies. Samples were processed using a protocol with or without a paraformaldehyde-based fixation step, and matching sample pairs were analyzed by flow cytometry. Our results show that paraformaldehyde-based fixation, in comparison to matched unfixed samples, did not significantly affect population distribution and frequency for: B cells, Plasmablasts, Dendritic cells, NK cells, Granulocytes, Neutrophils, Eosinophils, or Hematopoietic Stem/Progenitor Cells. However, fixation led to significant marker shifts in the subpopulation distribution in CD4, T regulatory, CD8, Monocytes, and Basophils. These results indicate the importance of pre-experimental assessment of fixation-introduced artifacts in the flow cytometry output when considering the feasibility of fresh processing. This is especially important for samples analyzed using comprehensive exploratory immunoprofiling panels.

Transplacental transfer of postpartum inhibitors to factor VIII.

Acquired haemophilia due to antibodies directed against coagulation factor VIII is a well-recognized cause of severe haemorrhage in adults but an uncommon cause of bleeding in children. We present the cases of a mother with a life-threatening postpartum haemorrhage due to an autoantibody to factor VIII and her newborn who developed symptomatic bleeding after a minor surgical intervention as a result of transplacental transfer of the autoantibody. Both patients were treated with infusions of recombinant factor VIIa to control bleeding. The mother required immunosuppressive therapy to decrease inhibitor levels and the infant's levels decreased over time without specific treatment. We also provide a concise review of postpartum haemophilia and transplacental transmission of factor VIII autoantibodies to the neonate--a rare but potentially life-threatening complication of acquired haemophilia in women of childbearing age.

Multiple births among adolescent women in Illinois.

OBJECTIVE: To examine the occurrence of multiple births among adolescents using birth as the unit of analysis and to examine the association between maternal race/ethnicity and parity and the occurrence of multiple births among women less than 20 years of age. STUDY DESIGN: Computerized birth certificate files without personal identifiers were obtained from the Illinois Department of Public Health totaling 1,103,333 live births from 1989 to 1994. RESULTS: A total of 13.3% of births during this time were to mothers less than 20 years of age. The overall maternal multiple birth rate was 8.2/1,000 births. There were statistically significant differences in the numbers of pregnancies resulting in live, multiple births among black, Hispanic and white teenage mothers. There was a linear increase in maternal multiple birth rates among black (P < .0001) and Hispanic (P < .001) teenage mothers by parity as well as a linear increase among black (P < .0001), Hispanic (P < .0236) and white (P < .049) populations by age of the mother. The age- and parity-specific maternal multiple birth rate ranged from 4.4 per 1,000 pregnancies for Hispanic teenage mothers less than 18 years of age to 11.9 per 1,000 pregnancies for black teenage mothers 19 years of age. At 0 and 1 parity, black women less than 20 years of age were at the highest risk for multiple births as compared to Hispanic and white mothers. CONCLUSION: This is the first study showing ethnic and racial differences in the rates of multiple births among teenage mothers. As in older women, increased age and a higher parity were associated with a higher probability of multiple birth among adolescents.

PIP: Selected demographic characteristics associated with multiple births among female adolescents were investigated through a review of computerized birth certificate files (n = 1,103,333) obtained from the Illinois (US) Department of Public Health for 1989-94. 13.3% of these births were to women under 20 years of age. The overall multiple birth rate was 8.2/1000 births. Among women who had a multiple birth, approximately 1/6 of Black mothers, 1/11 of Hispanic mothers, and 1/25 of White mothers were teenagers. Noted was a linear increase in multiple birth rates among Black (p 0.0001) and Hispanic (p 0.001) teenage mothers by parity as well as a linear increase by maternal age among Black (p 0.0001), Hispanic (p 0.0236), and White (p 0.049) mothers. The age- and parity-specific multiple birth rate ranged from 4.4/1000 pregnancies for Hispanic women under 18 years of age to 11.9/1000 pregnancies among Black women 19 years old. At parities 0 and 1, Black women under 20 years of age were at greatest risk of multiple births. These findings indicate that the etiologic factors influencing the occurrence of multiple births may differ among teenagers compared to their older counterparts and in teenagers of different racial or ethnic backgrounds.