ABSTRACT
Most human T cell leukemia virus type 1 (HTLV-1) infected subjects remain asymptomatic throughout their lives, with a few individuals developing HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) or adult T cell leukemia. Lymphocytes from about half of HTLV-1 infected subjects spontaneously proliferate in vitro, and how this phenomenon relates to symptomatic disease outcome and viral burden is poorly understood. Spontaneous proliferation was measured in lymphocyte subsets, and these findings were correlated with HTLV-1 proviral load and Tax expression in PBMCs. We found that in addition to previously described vigorous CD8+ T cell spontaneous proliferation, natural killer (NK) cells spontaneously proliferated to a similar high level, resulting in expansion of CD56-expressing NK cells. Spontaneous NK cell proliferation positively correlated with HTLV-1 proviral load but not with Tax expression or the presence of HAM/TSP. The strongest correlate with clinical outcome in this cohort was the ability of cells to express Tax, while HTLV-1 proviral load was more closely related to spontaneous NK cell proliferation. These results demonstrate that spontaneous proliferation, Tax expression, and proviral load are inter-related but not equivalent, and that spontaneous lymphocyte proliferation is not restricted to T cells, the targets of HTLV-1 infection.
Subject(s)
Human T-lymphotropic virus 1/immunology , Human T-lymphotropic virus 1/pathogenicity , Killer Cells, Natural/immunology , Killer Cells, Natural/virology , Paraparesis, Tropical Spastic/pathology , Paraparesis, Tropical Spastic/virology , Adult , Aged , Aged, 80 and over , CD56 Antigen/analysis , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/virology , Cell Proliferation , Female , Gene Expression , Gene Products, tax/biosynthesis , Humans , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/virology , Lymphocyte Subsets/immunology , Lymphocyte Subsets/virology , Male , Middle Aged , Paraparesis, Tropical Spastic/immunology , Young AdultABSTRACT
BACKGROUND: Understanding participation in a prospective study is crucial to maintaining and improving retention rates. In 1990-92, following attempted blood donation at five blood centers, we enrolled 155 HTLV-I, 387 HTLV-II and 799 HTLV seronegative persons in a long-term prospective cohort. METHODS: Health questionnaires and physical exams were administered at enrollment and 2-year intervals through 2004. To examine factors influencing attendance at study visits of the cohort participants we calculated odds ratios (ORs) with generalized estimated equations (GEE) to analyze fixed and time-varying predictors of study visit participation. RESULTS: There were significant independent associations between better visit attendance and female gender (OR = 1.31), graduate education (OR = 1.86) and income > $75,000 (OR = 2.68). Participants at two centers (OR = 0.47, 0.67) and of Black race/ethnicity (OR = 0.61) were less likely to continue. Higher subject reimbursement for interview was associated with better visit attendance (OR = 1.84 for $25 vs. $10). None of the health related variables (HTLV status, perceived health status and referral to specialty diagnostic exam for potential adverse health outcomes) significantly affected participation after controlling for demographic variables. CONCLUSION: Increasing and maintaining participation by minority and lower socioeconomic status participants is an ongoing challenge in the study of chronic disease outcomes. Future studies should include methods to evaluate attrition and retention, in addition to primary study outcomes, including qualitative analysis of reasons for participation or withdrawal.
Subject(s)
HTLV-I Infections , HTLV-II Infections , Patient Acceptance of Health Care/statistics & numerical data , Research Subjects , Adolescent , Adult , Cohort Studies , Female , Health Status , Humans , Male , Middle Aged , Multivariate Analysis , Odds Ratio , Prospective Studies , Research Subjects/psychology , Sex Factors , Socioeconomic Factors , Surveys and Questionnaires , United States , Young AdultABSTRACT
BACKGROUND: New regulatory requirements for donor eligibility challenge blood centers to recruit and retain enough donors. This study evaluated correlations between overall satisfaction with the donation process and donor demographics and the effect of both on a donor's intent to return. STUDY DESIGN AND METHODS: An anonymous, self-administered questionnaire was given to donors at multiple sites of one blood center over a 3-week period. First-time and repeat donors were asked questions on demographic characteristics, satisfaction with the current donation process, motivation for current and future donations, and intent to return. RESULTS: More than 75 percent of donors rated the overall donation process at 9 or 10 on a scale of 10 (mean, 9.19; standard deviation, 1.09), with female, high school-educated, and first-time donors giving higher satisfaction ratings than male, college-educated, and repeat donors, respectively (all p < 0.001). Donor satisfaction was correlated with intent to return for another donation (p = 0.002). For the current donation, donors rated altruistic motivations most highly. Medical testing was the most highly rated incentive for future donations, followed by frequent donor programs and convenient donation times and locations; preferences varied by demographic subgroup. CONCLUSIONS: Blood donor satisfaction varies among demographic and donation history subgroups and is positively correlated with the intent to return for future donation. Although the primary motivation among all donors was altruism, incentives to future donation may need to be tailored according to demographic subgroups.
