Determinants of Bed Net Use in Southeast Nigeria following Mass Distribution of LLINs: Implications for Social Behavior Change Interventions

Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the global malaria control strategy. LLIN ownership, however, does not necessarily guarantee use. Thus, even in the ideal setting in which universal coverage with LLINs has been achieved, maximal malaria protection will only be achieved if LLINs are used both correctly and consistently. This study investigated the factors associated with net use, independent of net ownership. Data were collected during a household survey conducted in Ebonyi State in southeastern Nigeria in November 2011 following a statewide mass LLIN distribution campaign and, in select locations, a community-based social behavior change (SBC) intervention. Logistic regression analyses, controlling for household bed net ownership, were conducted to examine the association between individual net use and various demographic, environmental, behavioral and social factors. The odds of net use increased among individuals who were exposed to tailored SBC in the context of a home visit (OR = 17.11; 95% CI 4.45-65.79) or who received greater degrees of social support from friends and family (ptrend < 0.001). Factors associated with decreased odds of net use included: increasing education level (ptrend = 0.020), increasing malaria knowledge level (ptrend = 0.022), and reporting any disadvantage of bed nets (OR = 0.39; 95% CI 0.23-0.78). The findings suggest that LLIN use is significantly influenced by social support and exposure to a malaria-related SBC home visit. The malaria community should thus further consider the importance of community outreach, interpersonal communication and social support on adoption of net use behaviors when designing future research and interventions.

'A living death': a qualitative assessment of quality of life among women with trichiasis in rural Niger

BACKGROUND

Prior to blindness, trachoma is thought to profoundly affect women's abilities to lead normal lives, but supporting evidence is lacking. To better understand the effects of trichiasis, we asked women to define quality of life, how trichiasis affects this idea and their perceptions of eyelid surgery.

METHODS

Operated and unoperated women were purposively selected for in-depth interviews. These were audio-recorded and transcribed, and codes were identified and applied to the transcripts. Overarching themes, commonalities and differences were identified and matched to quotations.

RESULTS

Twenty-three women were interviewed. Quality of life was defined as health, security, family, social status and religious participation. Trichiasis caused severe pain and loss of health, leading to loss of security. This affected social, economic and religious activities and caused burden on their families. Surgery improved quality of life, even in cases of surgical failure or recurrent disease.

CONCLUSIONS

Trichiasis disables most women, even those reporting fewer or less-severe symptoms. While women in rural Niger often live in extreme poverty, trichiasis exacerbates the situation, making women unable to work and undermining their social status. It adds to family burden, as women lose the ability to meaningfully contribute to the household and require additional family resources for their care.

Malaria prevalence, anemia and baseline intervention coverage prior to mass net distributions in Abia and Plateau States, Nigeria

Background

Nigeria suffers the world’s largest malaria burden, with approximately 51 million cases and 207,000 deaths annually. As part of the country’s aim to reduce by 50% malaria-related morbidity and mortality by 2013, it embarked on mass distribution of free long-lasting insecticidal nets (LLINs).

Methods

Prior to net distribution campaigns in Abia and Plateau States, Nigeria, a modified malaria indicator survey was conducted in September 2010 to determine baseline state-level estimates of Plasmodium prevalence, childhood anemia, indoor residual spraying (IRS) coverage and bednet ownership and utilization.

Results

Overall age-adjusted prevalence of Plasmodium infection by microscopy was similar between Abia (36.1%, 95% CI: 32.3%–40.1%; n = 2,936) and Plateau (36.6%, 95% CI: 31.3%–42.3%; n = 4,209), with prevalence highest among children 5-9 years. P. malariae accounted for 32.0% of infections in Abia, but only 1.4% of infections in Plateau. More than half of children ≤10 years were anemic, with anemia significantly higher in Abia (76.9%, 95% CI: 72.1%–81.0%) versus Plateau (57.1%, 95% CI: 50.6%–63.4%). Less than 1% of households in Abia (n = 1,305) or Plateau (n = 1,335) received IRS in the 12 months prior to survey. Household ownership of at least one bednet of any type was 10.1% (95% CI: 7.5%–13.4%) in Abia and 35.1% (95% CI: 29.2%-41.5%) in Plateau. Ownership of two or more bednets was 2.1% (95% CI: 1.2%–3.7%) in Abia and 14.5% (95% CI: 10.2%–20.3%) in Plateau. Overall reported net use the night before the survey among all individuals, children <5 years, and pregnant women was 3.4%, 6.0% and 5.7%, respectively in Abia and 14.7%, 19.1% and 21.0%, respectively in Plateau. Among households owning nets, 34.4% of children <5 years and 31.6% of pregnant women in Abia used a net, compared to 52.6% of children and 62.7% of pregnant women in Plateau.

Conclusions

These results reveal high Plasmodium prevalence and childhood anemia in both states, low baseline coverage of IRS and LLINs, and sub-optimal net use—especially among age groups with highest observed malaria burden.

Estimation of insecticide persistence, biological activity and mosquito resistance to PermaNet® 2 long-lasting insecticidal nets over three to 32 months of use in Ethiopia

Background

Information is needed on the expected durability of insecticidal nets under operational conditions. The persistence of insecticidal efficacy is important to estimate the median serviceable life of nets under field conditions and to plan for net replacement.

Methods

Deltamethrin residue levels were evaluated by the proxy method of X-ray fluorescence spectrometry on 189 nets used for three to six months from nine sites, 220 nets used for 14-20 months from 11 sites, and 200 nets used for 26-32 months from ten sites in Ethiopia. A random sample of 16.5-20% of nets from each time period (total 112 of 609 nets) were tested by bioassay with susceptible mosquitoes, and nets used for 14-20 months and 26-32 months were also tested with wild caught mosquitoes.

Results

Mean insecticide levels estimated by X-ray fluorescence declined by 25.9% from baseline of 66.2 (SD 14.6) mg/m² at three to six months to 44.1 (SD 21.2) mg/m² at 14-20 months and by 30.8% to 41.1 (SD 18.9) mg/m² at 26-32 months. More than 95% of nets retained greater than 10 mg/m2 of deltamethrin and over 79% had at least 25 mg/m2 at all time periods. By bioassay with susceptible Anopheles, mortality averaged 89.0% on 28 nets tested at three to six months, 93.3% on 44 nets at 14-20 months and 94.1% on 40 nets at 26-32 months. With wild caught mosquitoes, mortality averaged 85.4% (range 79.1 to 91.7%) at 14-20 months but had dropped significantly to 47.2% (39.8 to 54.7%) at 26-32 months.

Conclusions

Insecticide residue level, as estimated by X-ray fluorescence, declined by about one third between three and six months and 14-20 months, but remained relatively stable and above minimum requirements thereafter up to 26-32 months. The insecticidal activity of PermaNet® 2.0 long-lasting insecticidal nets in the specified study area may be considered effective to susceptible mosquitoes at least for the duration indicated in this study (32 months). However, results indicated that resistance in the wild population is already rendering nets with optimum insecticide concentrations less effective in practice.

Physical durability of PermaNet 2.0 long-lasting insecticidal nets over three to 32 months of use in Ethiopia

Background

Ethiopia scaled up net distribution markedly starting in 2006. Information on expected net life under field conditions (physical durability and persistence of insecticidal activity) is needed to improve planning for net replacement. Standardization of physical durability assessment methods is lacking.

Methods

Permanet®2.0 long-lasting insecticidal bed nets (LLINs), available for distribution in early 2007, were collected from households at three time intervals. The number, size and location of holes were recorded for 189 nets used for three to six months from nine sites (2007) and 220 nets used for 14 to 20 months from 11 sites (2008). In 2009, a “finger/fist” sizing method classified holes in 200 nets used for 26 to 32 months from ten sites into small (<2 cm), medium (> = 2 to < =10 cm) and large (>10 cm) sizes. A proportionate hole index based on both hole number and area was derived from these size classifications.

Results

After three to six months, 54.5% (95% CI 47.1-61.7%) of 189 LLINs had at least one hole 0.5 cm (in the longest axis) or larger; mean holes per net was 4.4 (SD 8.4), median was 1.0 (Inter Quartile Range [IQR] 0–5) and median size was 1 cm (IQR 1–2). At 14 to 20 months, 85.5% (95% CI 80.1-89.8%) of 220 nets had at least one hole with mean 29.1 (SD 50.1) and median 12 (IQR 3–36.5) holes per net, and median size of 1 cm (IQR 1–2). At 26 to 32 months, 92.5% of 200 nets had at least one hole with a mean of 62.2 (SD 205.4) and median of 23 (IQR 6–55.5) holes per net. The mean hole index was 24.3, 169.1 and 352.8 at the three time periods respectively. Repairs were rarely observed. The majority of holes were in the lower half of the net walls. The proportion of nets in ‘poor’ condition (hole index >300) increased from 0% at three to six months to 30% at 26 to 32 months.

Conclusions

Net damage began quickly: more than half the nets had holes by three to six months of use, with 40% of holes being larger than 2 cm. Holes continued to accumulate until 92.5% of nets had holes by 26 to 32 months of use. An almost complete lack of repairs shows the need for promoting proper use of nets and repairs, to increase LLIN longevity. Using the hole index, almost one third of the nets were classed as unusable and ineffective after two and a half years of potential use.

Making sense of HIV in southeastern Nigeria: fictional narratives, cultural meanings, and methodologies in medical anthropology

Fictional narratives have rarely been used in medical anthropological research. This article illustrates the value of such narratives by examining how young people in southeastern Nigeria navigate the cultural resources available to them to make sense of HIV in their creative writing. Using thematic data analysis and narrative-based methodologies, it analyzes a sample (N = 120) from 1,849 narratives submitted by Nigerian youth to the 2005 Scenarios from Africa scriptwriting contest on the theme of HIV. The narratives are characterized by five salient themes: tragedy arising from the incompatibility of sex outside marriage and kinship obligations; female vulnerability and blame; peer pressure and moral ambivalence; conservative Christian sexual morality; and the social and family consequences of HIV. We consider the strengths and limitations of this narrative approach from a theoretical perspective and by juxtaposing our findings with those generated by Daniel Jordan Smith using standard ethnographic research methods with a similar Igbo youth population.

Monitoring of mass distribution interventions for trachoma in Plateau State, Nigeria

Mass drug administration (MDA) with antibiotics is a key component of the SAFE strategy for trachoma control. Guidelines recommend that where MDA is warranted the whole population be targeted with 80% considered the minimum acceptable coverage. In other countries, MDA is usually conducted by salaried Ministry of Health personnel (MOH). In Plateau State, Nigeria, the existing network of volunteer Community Directed Distributors (CDD) was used for the first trachoma MDA. We conducted a population-based cluster random survey (CRS) of MDA participation to determine the true coverage and compared this to coverage reported from CDD registers. We surveyed 1,791 people from 352 randomly selected households in 24 clusters in three districts in Plateau State in January 2011, following the implementation of MDA. Households were enumerated and all individuals present were asked about MDA participation. Household heads were questioned about household-level characteristics and predictors of participation. Individual responses were compared with the CDD registers. MDA coverage was estimated as 60.3% (95% CI 47.9–73.8%) by the survey compared with 75.8% from administrative program reports. CDD registration books for comparison with responses were available in 19 of the 24 clusters; there was a match for 658/682 (96%) of verifiable responses. CDD registers did not list 481 (41.3%) of the individuals surveyed. Gender and age were not associated with individual participation. Overall MDA coverage was lower than the minimum 80% target. The observed discrepancy between the administrative coverage estimate from program reports and the CRS was largely due to identification of communities missed by the MDA and not reported in the registers. CRS for evaluation of MDA provides a useful additional monitoring tool to CDD registers. These data support modification of distributor training and MDA delivery to increase coverage in subsequent rounds of MDA.

The World Health Organization recommends that mass drug administration for trachoma control reach a minimum of 80% of the target population. Previous evaluations of MDA coverage have demonstrated that administrative reports can bias coverage estimates. A survey of participation in mass drug administration for trachoma control was implemented in three districts in Plateau State, Nigeria in 2011 to validate coverage calculated from treatment registers. A total of 352 households were surveyed from 24 randomly selected communities. Heads of household were interviewed to identify household-level characteristics and predictors of participation. Individual household members were enumerated and those present at the time of interview were asked to report individual participation in the MDA. Responses were verified against the community-drug distributor registration log. Approximately 60% of the sample reported receiving either tetracycline eye ointment or azithromycin for trachoma control. Administrative data on treatment estimated coverage at 76% for the three LGAs. The discrepancy between the coverage estimate from administrative data (calculated by the program) and the survey data suggest that cluster random surveys of MDA provide a useful monitoring tool to validate administrative data on treatment coverage. These data support modification of distributor training and MDA delivery to increase coverage in subsequent rounds of MDA.

Validity of Expanded Program on Immunization Contact Method health behavior estimates in Mali

BACKGROUND

In the developing world, household surveys provide high-quality health behavior data integral to public health program management. The Expanded Program on Immunization Contact Method (EPI-CM) is a proposed, less resource-intensive method in which health center staff incorporate health behavior questions into routine vaccination activities. No systematic evaluation of EPI-CM validity has yet been conducted.

METHODS

We used concurrent household survey and EPI-CM to collect data on 4 infant health behaviors in Mali at 2 time points (8 total comparisons). Studied health behaviors were bednet use, obtaining care for fever, obtaining care for a respiratory complaint, and using oral rehydration solution for diarrhea. Household survey and EPI-CM estimates were considered equivalent if a 95% confidence interval about the difference in estimated proportions fell within the interval (-.10, .10).

RESULTS

EPI-CM estimates were higher than household survey estimates for 7 of 8 unadjusted paired estimates; estimates of bednet use in 2009 met a priori equivalence criteria in a setting of high bednet use (90.5%). When we restricted household survey data to infants up-to-date on vaccinations, estimates for behaviors other than bednet use remained substantially different.

CONCLUSIONS

We were unable to demonstrate that EPI-CM, as implemented, consistently produces data comparable with household survey data.

Effect of the Expanded Program on Immunization Contact Method of data collection on health behaviors in Mali

BACKGROUND

The Expanded Program on Immunization Contact Method (EPI-CM) is a proposed monitoring and program management tool for developing countries. The method involves health workers tallying responses to questions about health behaviors during routine immunizations and providing targeted counseling. We evaluated whether asking caretakers about health behaviors during EPI visits led to changes in those behaviors.

METHODS

We worked in 2 districts in Mali: an intervention district where during immunization visits workers asked about 4 health behaviors related to bed net use, fever, respiratory disease, and diarrhea, and a control district where workers conducted routine immunization activities without health behavior questions. To evaluate the effect of EPI-CM, we conducted a cross-sectional household survey at baseline and 1 year postintervention. We used multivariate logistic regression to compare between districts the change over 1 year in 4 health behaviors: use of insecticide-treated nets, appropriate fever treatment, care-seeking for respiratory complaints, and appropriate diarrhea treatment.

RESULTS

There were no significant differences between the 2 districts in the change in the 4 health behaviors when controlling for age, sex, maternal education and occupation, immunization history, and wealth.

CONCLUSIONS

We found no evidence that EPI-CM increases healthy behaviors. Further evaluation of other potential benefits and costs of EPI-CM is warranted.

Factors associated with mosquito net use by individuals in households owning nets in Ethiopia

BACKGROUND

Ownership of insecticidal mosquito nets has dramatically increased in Ethiopia since 2006, but the proportion of persons with access to such nets who use them has declined. It is important to understand individual level net use factors in the context of the home to modify programmes so as to maximize net use.

METHODS

Generalized linear latent and mixed models (GLLAMM) were used to investigate net use using individual level data from people living in net-owning households from two surveys in Ethiopia: baseline 2006 included 12,678 individuals from 2,468 households and a sub-sample of the Malaria Indicator Survey (MIS) in 2007 included 14,663 individuals from 3,353 households. Individual factors (age, sex, pregnancy); net factors (condition, age, net density); household factors (number of rooms [2006] or sleeping spaces [2007], IRS, women's knowledge and school attendance [2007 only], wealth, altitude); and cluster level factors (rural or urban) were investigated in univariate and multi-variable models for each survey.

RESULTS

In 2006, increased net use was associated with: age 25-49 years (adjusted (a) OR = 1.4, 95% confidence interval (CI) 1.2-1.7) compared to children U5; female gender (aOR = 1.4; 95% CI 1.2-1.5); fewer nets with holes (Ptrend = 0.002); and increasing net density (Ptrend < 0.001). Reduced net use was associated with: age 5-24 years (aOR = 0.2; 95% CI 0.2-0.3). In 2007, increased net use was associated with: female gender (aOR = 1.3; 95% CI 1.1-1.6); fewer nets with holes (aOR [all nets in HH good] = 1.6; 95% CI 1.2-2.1); increasing net density (Ptrend < 0.001); increased women's malaria knowledge (Ptrend < 0.001); and urban clusters (aOR = 2.5; 95% CI 1.5-4.1). Reduced net use was associated with: age 5-24 years (aOR = 0.3; 95% CI 0.2-0.4); number of sleeping spaces (aOR [per additional space] = 0.6, 95% CI 0.5-0.7); more old nets (aOR [all nets in HH older than 12 months] = 0.5; 95% CI 0.3-0.7); and increasing household altitude (Ptrend < 0.001).

CONCLUSION

In both surveys, net use was more likely by women, if nets had fewer holes and were at higher net per person density within households. School-age children and young adults were much less likely to use a net. Increasing availability of nets within households (i.e. increasing net density), and improving net condition while focusing on education and promotion of net use, especially in school-age children and young adults in rural areas, are crucial areas for intervention to ensure maximum net use and consequent reduction of malaria transmission.

Operational issues and trends associated with the pilot introduction of zinc for childhood diarrhoea in Bougouni district, Mali

Zinc for the treatment of childhood diarrhoea was introduced in a pilot area in southern Mali to prepare for a cluster-randomized effectiveness study and to inform policies on how to best introduce and promote zinc at the community level. Dispersible zinc tablets in 14-tablet blister packs were provided through community health centres and drug kits managed by community health workers (CHWs) in two health zones in Bougouni district, Mali. Village meetings and individual counselling provided by CHWs and head nurses at health centres were the principal channels of communication. A combination of methods were employed to (a) detect problems in communication about the benefits of zinc and its mode of administration; (b) identify and resolve obstacles to implementation of zinc through existing health services; and (c) describe household-level constraints to the adoption of appropriate home-management practices for diarrhoea, including administration of both zinc and oral rehydration solution (ORS). Population-based household surveys with caretakers of children sick in the previous two weeks were carried out before and four months after the introduction of zinc supplementation. Household follow-up visits with children receiving zinc from the health centres and CHWs were conducted on day 3 and 14 after treatment for a subsample of children. A qualitative process evaluation also was conducted to investigate operational issues. Preliminary evidence from this study suggests that the introduction of zinc does not reduce the use of ORS and may reduce inappropriate antibiotic use for childhood diarrhoea. Financial access to treatments, management of concurrent diarrhoea and fever, and high use of unauthorized drug vendors were identified as factors affecting the effectiveness of the intervention in this setting. The introduction of zinc, if not appropriately integrated with other disease-control strategies, has the potential to decrease the appropriate presumptive treatment of childhood malaria in children with diarrhoea and fever in malaria-endemic areas.

Local terminology for medicines to treat fever in Bougouni District, Mali: implications for the introduction and evaluation of malaria treatment policies

OBJECTIVE

To explore Bambara language terminology and classification for locally available antimicrobial medicines in order to better target promotional messages and improve evaluation measures in Bougouni District, Mali.

METHODS

Mothers (n = 20) and drug vendors (n = 15) were asked to freelist medicines used to treat childhood illnesses, and to identify all medicines that corresponded to each of the listed terms from an array of medicines displayed with their packaging.

RESULTS

Each Bambara language medicine term can refer to numerous modern medicines, and each modern medicine has several Bambara names. The term nivakini (Nivaquine), often translated as 'chloroquine', refers to a wide range of medicines commonly used to treat malaria, many with no antimalarial effect. Antibiotics were also identified as common treatments for malaria. Mothers and vendors used slightly different terminology when discussing treatments for malaria, and sometimes employed the same term to refer to different medicines. Neither mothers nor vendors clearly differentiated between antimalarial medicines. Colour, shape and packaging play a large role in their recognition, classification and use.

CONCLUSIONS

Current household survey methods are likely to provide inaccurate estimates of appropriate treatment of febrile illness, and thus alternative approaches are recommended. In introducing new malaria treatments, malaria control programmes should differentiate recommended treatments from other medications through distinctive packaging, drug appearance and appropriate Bambara language terms.

Prescription and administration of a 14-day regimen of zinc treatment for childhood diarrhea in Mali

We evaluated prescription and correct dosing of a 14-day course of dispersible zinc tablets prescribed to young children with diarrhea by community and facility workers in rural, southern Mali, West Africa. One hundred twenty-three children were followed at home on days 3 and 14 after being prescribed zinc. The age-appropriate dose of zinc was dispensed in 94% of cases. Ninety-five percent of mothers dissolved the tablet in a small amount of water and gave it with a spoon. Only eight caretakers reported problems with zinc administration: either vomiting or refusal to take the tablets. Sixty-four percent of children received the full 14-day course of treatment, and more than 89% of children were given at least a 10-day course of zinc treatment. The levels of correct administration were very good but might be lower under non-research conditions.

Infusion of select leukemia-reactive TCR Vbeta+ T cells provides graft-versus-leukemia responses with minimization of graft-versus-host disease following murine hematopoietic stem cell transplantation

T-cell receptor (TCR) Vbeta-expression analysis by complementarity-determining region 3 (CDR3)-size spectratyping can identify the reactive populations in an immunologic response. This analysis was used in this study to characterize the Vbeta responses of C57BL/6 (B6) CD4+ and CD8+ T cells directed to either alloantigen (against [B6xDBA/2]F1; anti-H2d) or the syngeneic myeloid leukemia MMB3.19. Vbeta families exhibiting reactivity to the leukemia cells were then enriched for and administered in both syngeneic and allogeneic hematopoietic stem cell transplantation (HSCT) models to assess in vivo graft-versus-leukemia (GVL) potential. In syngeneic transplants, enrichment for pools of selected Vbeta families (Vbeta7, -11, and -13) of T cells or for a single Vbeta family (Vbeta7) of CD4+ T cells conveyed a beneficial GVL response to the recipients. Furthermore, in the haploidentical allogeneic model, both Vbeta6,7-enriched donor B6 T cells and Vbeta7-enriched CD4+ T cells exhibited significant GVL responses with concomitant minimization of graft-versus-host disease (GVHD) development compared with equal numbers of unfractionated T cells. These results suggest that CDR3-size spectratype analysis of and subsequent selection from donor T-cell repertoires can be an effective approach to separate GVL and GVHD potential following allogeneic HSCT.

Cross-protective murine graft-versus-leukemia responses to phenotypically distinct myeloid leukemia lines

A c-myc retrovirus-transformed myeloid leukemia line, MMB3.19, of C57BL/6 (B6) origin, was developed to investigate graft-versus-leukemia (GVL) activity in murine bone marrow transplantation (BMT) models. It was previously determined that both naive and leukemia-presensitized CD4+-enriched T cells are capable of mediating GVL activity to MMB3.19 challenge in both syngeneic (B6) and allogeneic (C3H.SW-->B6) strain combinations, with the latter coinciding with minimal graft-versus-host disease. In the present study, MMB3.19 and 2 other similarly derived, yet phenotypically diverse, B6 myeloid leukemia lines (MMB1.10 and MMB2.18) were investigated for potential shared tumor antigens in the syngeneic GVL model. Morphologically, all 3 tumor lines are blastic with high cytoplasmic:nuclear ratios, but MMB2.18 displays dendritic processes, whereas MMB1.10 and MMB3.19 have a more rounded appearance. Flow cytometric analysis of the 3 lines revealed constitutive surface molecule expression of Mac-1, Mac-2, F4/80, LFA-1, B7-1, B7-2, H2Kb, H2Db, and macrophage scavenger receptor, consistent with macrophage/monocyte lineages. Furthermore, each of the lines expresses H2I-Ab, but to varying degrees, with MMB2.18 cells having the lowest percentage (31.6%). In vitro 51Cr release assays using MMB3.19-primed T-cell effectors demonstrated equivalent specific lysis of all 3 leukemia-line target cells. In addition, enzyme-linked immunospot analysis of MMB3.19-primed CD4+ T cells revealed significantly increased frequencies of tumor-stimulated interleukin (IL)-2-, IL-4-, and interferon-gamma-secreting cells when restimulated with each of the 3 leukemia lines. Furthermore, when MMB3.19-primed CD4+ T cells were administered in a BMT setting, a protective GVL effect was seen in those mice challenged with MMB1.10, MMB2.18, or MMB3.19. Therefore, in vitro and in vivo experiments indicate that the 3 distinct myeloid leukemia lines share 1 or more common major histocompatibility complex class II-restricted tumor antigens that can elicit a cross-protective in vivo T-cell GVL response.

T-cell subsets mediate graft-versus-myeloid leukemia responses via different cytotoxic mechanisms

Analysis of the cytotoxic effector mechanisms by which T-cell subsets mediate graft-versus-leukemia (GVL) activity is complicated by systems that use unfractionated T cells and leukemias that express alloantigens in addition to tumor-specific antigens. In this study, we used MMB1.10, a myeloid leukemia of C57Bl/6 (B6) origin, to examine the cytolytic pathways employed by syngeneic GVL-mediating, and therefore tumor antigen-specific, T-cell subsets. Wright-Giemsa staining and flow cytometric analysis indicated that MMB1.10 cells exhibited the morphology and markers most consistent with a monocytic-myeloid origin. Although reverse transcription-polymerase chain reaction analysis revealed that MMB1.10 cells expressed tumor necrosis factor (TNF) receptor types I and H, in vitro assays suggested that these cells were resistant to TNF-alpha-mediated cytotoxicity. For study of in vivo GVL responses, mice were challenged with MMBl.10 cells, lethally irradiated, and administered anti-Thy-1-treated (T-cell-depleted) bone marrow (ATBM) either alone or in combination with T-cell subsets from MMB1.10-presensitized mice. In regard to CD4+ donor T cells, 4 x 10(6) MMB1.10-presensitized wild-type (wt) cells exhibited increased GVL responses and survival values relative to tumor-challenged recipients of ATBM only. CD4 T cells from either perforin-deficient (pfp0) or Fas ligand (FasL)-deficient (gld) mice exhibited a lower level of GVL activity but did not produce any long-term survivors. Recipients of 5 x 10(6) wt B6 CD8+ T cells had significantly improved survival relative to tumor-challenged mice that received ATBM only. The same dose of gld CD8+ T cells exhibited a reduced but significant level of GVL activity, whereas cells from mice that were perforin-deficient or cytotoxicity doubly deficient (cdd) (ie, lacking perforin and FasL) exhibited no discernable GVL activity. Doubling the gld CD8+ T-cell dose to 10(7) cells resulted in further improved survival of recipients. We conclude that GVL effects mediated by CD4+ T cells can depend on either perforin- or FasL-mediated mechanisms, whereas the CD8+ T-cell subset is heavily dependent on perforin-mediated cytotoxicity.

Initiation codon scanthrough versus termination codon readthrough demonstrates strong potential for major histocompatibility complex class I-restricted cryptic epitope expression

Accumulating evidence shows that the repertoire of major histocompatibility complex class I-restricted epitopes extends beyond conventional translation reading frames. Previously, we reported that scanthrough translation, where the initiating AUG of a primary open reading frame is bypassed, is most likely to account for the presentation of cryptic epitopes from alternative reading frames within the influenza A PR/8/34 nucleoprotein gene. Here, we confirm and extend these findings using an epitope cassette construct that features two well-defined CD8(+) T cell (TCD8+) epitopes in alternative reading frames, each preceded by a single start codon. Expression of one epitope depends on scanning of the ribosome over the first AUG with translation initiation occurring at the second AUG. We find that scanthrough translation has great potency in our system, with its impact being modulated, as predicted, by the base composition surrounding the first initiation codon, the number of start codons preceding the point of alternate reading frame initiation, and the efficiency with which the epitope itself is generated. Additionally, we investigated the efficiency of eukaryotic translation termination codons, to assess codon readthrough as a mechanism for cryptic epitope expression from 3' untranslated regions. In contrast with initiation codons, eukaryotic stop codons appear to be highly efficient at preventing expression of epitopes encoded in 3' untranslated regions, suggesting that 3' untranslated regions are not a common source of cryptic epitope substrate. We conclude that scanthrough is a powerful mechanism for the expression of epitopes encoded in upstream alternative open reading frames that may contribute significantly to TCD8+ responses and to tolerance induction.

Assessment of aerosol containment on the ELITE flow cytometer

Biohazardous aerosols generated during cell sorting have been of increased concern recently because of interest in sorting specimens containing human immunodeficiency virus type 1 (HIV-1). Current flow cytometers have features designed to contain such aerosols within the sorting chamber, but the efficacy of these features has not been established. Therefore, we tested aerosol containment by two ELITE flow cytometers (Coulter Cytometry, Inc., Hialeah, FL) during sorting of specimens containing high titers of bacteriophage. Agar plates confluent with susceptible Escherichia coli were used to detect infectious units released from the sorting chamber. Under recommended operating conditions very few infectious units were released from the sorting chambers. Release increased when the center stream was not optimally collected in a vacuum-exhausted tube or the chamber door was not completely closed. Failure of the negative pressure and high efficiency particle air (HEPA) filtration features had less of an effect. The data indicate that these standard safety features provide a rational expectation of safety for the flow cytometry operator.