Flt3 ligand promotes the generation of a distinct CD34(+) human natural killer cell progenitor that responds to interleukin-15.

Interleukin-15 (IL-15) is produced by human bone marrow (BM) stromal cells and can induce CD34(+) hematopoietic progenitor cells (HPCs) to differentiate into CD56(+)CD3(-) natural killer (NK) cells in the absence of stromal cells. IL-15 mediates its effects by signaling through the beta and gammac chains of the IL-2/15 receptor (R). The c-kit ligand (KL), also produced by stromal cells, enhances the expansion of NK cells from CD34(+) HPCs in the presence of IL-15, but alone has no ability to differentiate NK cells. Mice deficient in KL do not appear to have a quantitative deficiency in NK cells, suggesting that other stromal cell factors may contribute to NK cell expansion. Flt3 ligand (FL) is also produced by BM stromal cells and has homology with KL. Furthermore, mice with a targeted disruption of the FL gene have reduced numbers of NK cells. We evaluated here the effects of FL on human NK cell development and expansion from CD34(+) HPCs. Like KL, FL significantly enhanced the expansion of NK cells from CD34(+) HPCs in the presence of IL-15, compared with IL-15 alone. However, FL alone had no effect on NK cell differentiation. We therefore explored the mechanism by which FL promotes IL-15-mediated NK cell development. FL was found to induce IL-2/15Rbeta (CD122) expression on CD34(bright) HPCs. The CD34(bright) CD122(+) cell coexpressed CD38, but lacked expression of CD7, CD56, NK cell receptors (NKRs), or cytotoxic activity in the absence of IL-15. Using limiting dilution analysis in the presence of IL-15 alone, we demonstrated that the FL-induced CD34(bright)CD122(+) HPCs had an NK cell precursor frequency 20- to 60-fold higher than the CD34(dim/neg)CD122(-) HPCs and 65- to 235-fold higher than fresh CD34(+) HPCs. KL had similar effects as FL, but induced a significantly lower percentage of CD34(bright)CD122(+) cells (P

Adolescent pregnancy and early intervention programs benefit from case management.

Case Management methods are being adapted to effectively serve two vulnerable populations: pregnant and parenting adolescents, and infants and toddlers with disabilities of developmental delay and their families. This article describes the case management model developed by California's Adolescent Family Life program and discusses issues related to providing family-centered, community-based case management in early intervention programs.

A service tracking and referral form to monitor the receipt of services in a case management program.

Too often, systematic recording procedures are not developed which describe and assess the delivery of social work--and, more specifically, case management--services. The authors report on the Service Tracking and Referral Form developed by California's Adolescent Family Life Evaluation Project to document the receipt of services by pregnant adolescent clients as a result of case management intervention. The rationale and process underlying the development and use of the project's Service Tracking and Referral Form are discussed. Data are presented to illustrate the kinds of information which can be generated from the form. Finally, the authors discuss the form's utility and the possible uses of these types of data for case management, supervisory, administrative, and evaluative purposes.

Early adolescents' significant others: Grade and gender differences in perceived relationships with familial and nonfamilial adults and young people.

In order to provide a fuller and more satisfying description of the significant others in the social world of an adolescent, the Social Relations Questionnaire was developed and then administered to almost 3000 seventh-through tenth-graders in a midwestern suburban school district. The sample was randomly split in half and analyses were run on both halves separately to test for replicability. Results indicated that parents and siblings are almost always listed as significant others by adolescents in all four grade levels. Furthermore, the majority of adolescents listed at least one extended family adult and at least one nonrelated adult as important in their lives. The nonrelated adults lived closer to the adolescents and were seen more frequently and in more contexts than extended family members. Fewer extended family adults were listed in the older grades. Females listed more significant others than males both overall and in terms of both same- and opposite-sex nonrelated young people. As hypothesize, an increasing number of opposite-sex young people was listed as a function of grade level. Most nonrelated young people listed (a loose definition of peers) were from the same grade, same school, and same neighborhood as the respondent. The authors conclude that age-segregation in this community is not extreme (over 40% of the significant others listed were adults) and that the Social Relations Questionnaire provides a useful and holistic description of an adolescent's social world.