Phenotypic and cytotoxic characteristics of the immune cells of the human placenta.

Despite some functional impairment of the newborn's T-cell immune system, most infants survive the intrauterine and perinatal period without succumbing to infection or maternal lymphocyte engraftment. The placenta may play a crucial role in protecting the infant from microbial and histocompatibility antigens. Accordingly, we studied phenotypic and functional capacities of placental cells. Placentas were obtained from uncomplicated pregnancies. Matched cord blood and maternal peripheral blood were also obtained in many instances. Fresh minced placental tissue was washed and digested with collagenase and DNase and mononuclear cells were obtained by density gradient centrifugation. The average yield was 10(6) cells/g of tissue with greater than 80% viability. Chromosome analysis of five placental preparations indicated that these cells were of fetal rather than maternal origin. The isolated placental cells consisted of trophoblasts, lymphocytes (74 +/- 3%), monocytes (16 +/- 3%), and granulocytes (8 +/- 2%). E-rosette forming cells (T cells) made up 65 +/- 2% and surface membrane immunoglobulin positive cells made up 8 +/- 1% of the placental mononuclear cells. Fluorescent activated analysis of the mononuclear cells indicated less Leu 4-positive cells (Pan-T) 43 +/- 3%, and less Leu 3-positive (T-helper cells) (25 +/- 2%), than cord and maternal cell preparations. Leu-2, DR, and B1 positive cells were similar to those in cord and maternal blood. Leu 7 and especially Leu 11 positive cells, markers for natural killer cells, were abundant in placental cells, making up 4 +/- 0.7% and 20 +/- 3%, respectively. The Leu 7/Leu 11 ratio of the placental cells was different from either the maternal or cord blood cells. Natural killer activity of placental cells against a K562 natural killer target was low, despite the abundance of cells with NK markers. The K562 activity was low in the placental cells, similar to the low NK activity of maternal and cord cells. Molt 4f killer activity was near normal. Lectin-dependent cytotoxicity using an EL-4 cell target plus PHA was low in placentas, compared to normal, maternal, or cord cell cytotoxicity. Matched samples indicated that LDCC activity was mother greater than cord greater than placenta. Antibody-dependent cytotoxicity (Raji target) of placental cells showed low activity, and again the paired studies indicated that normal controls greater than maternal greater than cord greater than placenta cytotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)