[Analysis on survival time and influencing factors among reported HIV/AIDS in Yunnan Province, 1989-2021].

Objective: To analyze the survival time of reported HIV/AIDS and influencing factors of Yunnan Province from 1989 to 2021. Methods: The data were extracted from the Chinese HIV/AIDS comprehensive response information management system. The retrospective cohort study was conducted. The life table method was applied to calculate the survival probability. Kaplan-Meier was used to draw survival curves in different situations. Furthermore, the Cox proportion hazard regression model was constructed to identify the factors related to survival time. Results: Of the 174 510 HIV/AIDS, the all-cause mortality density was 4.23 per 100 person-years, the median survival time was 20.00 (95%CI:19.52-20.48) years, and the cumulative survival rates in 1, 10, 20, and 30 years were 90.75%, 67.50%, 47.93% and 30.85%. Multivariate Cox proportional risk regression model results showed that the risk of death among 0-14 and 15-49 years old groups were 0.44 (95%CI: 0.34-0.56) times and 0.51 (95%CI:0.50-0.52) times of ≥50 years old groups. The risk for death among the first CD4+T lymphocytes counts (CD4) counts levels of 200-349 cells/µl, 350-500 cells/µl and ≥501 cells/µl groups were 0.52 (95%CI: 0.50-0.53) times, 0.41 (95%CI: 0.40-0.42) times and 0.35 (95%CI: 0.34-0.36) times of 0-199 cells/µl groups. The risk of death among the cases that have not received antiretroviral therapy (ART) was 11.56 (95%CI: 11.26-11.87) times. The risk for death among the cases losing to ART, stopping to ART, both losing and stopping ART was 1.66 (95%CI:1.61-1.72) times, 2.49 (95%CI:2.39-2.60) times, and 1.65 (95%CI:1.53-1.78) times of the cases on ART. Conclusions: The influencing factors for the survival time of HIV/AIDS cases were age at diagnosis in Yunnan province from 1989 to 2021. The first CD4 counts levels, antiretroviral therapy, and ART compliance. Early diagnosis, early antiretroviral therapy, and increasing ART compliance could extend the survival time of HIV/AIDS cases.

[HIV-1 gene subtypes among newly reported HIV/AIDS cases in two border areas of Yunnan province].

Objective: To explore the features of distribution on HIV-1 gene subtypes among newly reported HIV/AIDS cases in the border areas of Yunnan province. Methods: A total of 233 newly reported HIV/AIDS cases aged 18 or more were consecutively included in the border counties of Dehong Dai and Jingpo autonomous prefecture (Dehong prefecture), Honghe Hani and Yi autonomous prefecture (Honghe prefecture) of Yunnan province from November 2015 to October 2016. HIV-1 RNA was extracted with pol and env genes amplified. HIV-1 gene subtypes were determined through phylogenetic analysis. Results: A total of 146 out of 233 specimens were genotyped successfully. HIV-1 was found to have had 8 gene subtypes in Dehong prefecture, with the unique recombinant forms (URFs) as the predominant (52.8%, 57/108) type, including 56.8% (21/37) of the cases with Chinese ethnicity and another 50.7% (36/71) were Myanmar citizens. Four HIV-1 gene subtypes were detected in Honghe prefecture, with CRF01_AE as predominant (71.1%, 27/38), including 81.0% (17/21) Vietnamese and 58.8% (10/17) Chinese. Differences on the distribution of HIV-1 gene subtypes were seen statistically significant between Dehong prefecture and Honghe prefecture (χ(2)=61.072, P<0.001). Conclusions: The distribution of HIV-1 gene subtypes showed big difference in the two border areas of Yunnan province, suggesting that both Chinese or non- Chinese citizens living in the area should be taken good care of, in terms of HIV/AIDS prevention and control.

[HIV and syphilis infection and related medical treatment status of low-fee female sex workers in three provinces of China, 2012-2015].

Objective: To understand the HIV and syphilis infection and related treatment status of low-fee female sex workers (FSWs) in 3 provinces of China. Methods: Four cross-sectional survey data of low-fee FSWs from six cities (counties) in Guangxi, Yunnan and Hunan Province between October 2012 and July 2015 were obtained from the national science and technology major special project intervention study for reducing sexually transmitted diseases (STDs) and acquired immunodeficiency syndrome (AIDS) in low-fee FSWs' database, which included social demographic characteristics, sexual service characteristics and related medical care seeking behaviors, etc. A total of 2 050 subjects were included in the database. Results: The age of the subjects was (35.16±9.76) years old, with a minimum age of 15 and a maximum age of 67. Those who use condoms every time in commercial sex accounted for 58.9% (n=1 206). Among the reasons of not using condom, the proportion of client reluctant to use was the highest (81.0% (n=682)). Only 38.1% (n=782) was tested for HIV in the last six months. HIV confirmed positive rate was 6.8% (n=139), previous positive accounts for 76.3% (n=106). Rate of antiviral therapy was 55.4% (n=77). By the end of 2015, the loss rate of antivirus treatment was 18.2% (n=14). Those who self-reported symptoms of sexually transmitted diseases in the last 6 months accounted for 9.4% (n=191). 50.3% (n=96) of reporters chose to go to formal hospitals, 23.0% (n=44) chose to go to private clinics and 20.4% (n=39) chose their own medication. The syphilis infection rate was 13.5% (n=277), among them, 91.3% (n=253) were asymptomatic. Conclusion: Among low-fee FSWs, the rates of HIV and syphilis infection are higher, the condom consistent use rate, HIV antibodies and syphilis test rate are lower. In this group, active seeking medical idea is poor, the rate of anti-virus treatment and the rate of seeking medical treatment in formal medical institutions is low.

[Changes of proportion regarding consistent condom use and syphilis infection among low-fee female sex workers aged 35 and above].

Objective: To investigate the changes of proportion on both consistent condom use and syphilis infection among low-fee female sex workers aged 35 and above (LFSW), in order to provide evidence for targeted intervention strategies. Methods: A total of six cities-Liuzhou city and Pingnan couty of Guigang city of Guangxi Zhuang Autonomous Region, Jinghong city of Xishuangbanna Dai autonomous prefecture and Dali city of Dali Bai autonomous prefecture of Yunnan province, Zhangjiajie city and Jianghua Yao autonomous county of Yongzhou city Hunan province were involved in this study, with 60 eligible participants needed in each city, estimated through a pre-study. The first cross-sectional survey was completed from October 2012 to January 2013. Face-to-face questionnaire interview was carried out to collect information on socio-demography, work-related information and condom use situation. Blood was collected for syphilis testing. The second cross-sectional survey was carried out from June to September, 2015 under the same procedure. Results: A total of 371 and 403 eligible participants were included in the first and second survey, respectively. When comparing the two surveys, we noticed that the average age showed a slight change, from 42.4 years to 43.8 years old (t=3.537, P<0.001) and the average price for every commercial sex exchange increased from 36.8 RMB to 49.5 RMB (t=11.961, P<0.001). In the first survey, 46.9% (174/371) of the participants had more than two years of experience working as LFSW, compared to 61.3% (247/403) in the second survey (χ(2)=16.125, P<0.001). Also, 46.9% (174/371) of the participants consistently used condoms with clients in the past month in the first survey versus 64.3% (259/403) (χ(2)=23.641, P<0.001) in the second one. Rates of syphilis infection were found from 15.9% (59/371) in the first survey reduced to 7.2% (29/403) in the second survey (χ(2)=14.533, P<0.001). Conclusion: Compared with the first survey, the proportion of consistent condoms use showed an increase. Although the proportion of syphilis infection decreased in the second survey, the scope did not meet the criteria on syphilis, set by the government. Targeted intervention strategies on condom promotion and syphilis control should be implemented consistently in this population.

[Knowledge, related behavior and on AIDS/HIV infection among rural adults with Derung minority, in Yunnan province, 2016].

Objective: To understand the related risk behaviors, knowledge and status of HIV/AIDS infection among rural adults of Derung minority, to provide relevant messages for the development of HIV/AIDS intervention strategy in this minority group. Methods: We used system sampling method to conduct a cross-sectional survey in 6 administration villages of Derung Township, Gongshan Derung and Nu Autonomous County in Nujiang Lisu Autonomous Prefecture of Yunnan Province, with a sample size estimated as 383. Adult residents with Derung minority in six villages of Gongshan County were involved, with relevant information collected through door-to-door visit. HIV antibody was tested and SPSS 17.0 was used for statistical analysis. Results: Information on 394 valid respondents was collected, with age as between 18 and 65 (34.39±9.74), 80.7% (318/394) as married, 54.0% (213/394) having had primary school education, 13.2% (52/394) as migrant workers. In this population, the overall HIV infection rate appeared as 0.5% (2/400), mainly through sexually transmission. The rate of awareness on HIV/AIDS was 69.8% (275/394), mainly through free publicized materials 50.0% (197/394). Rates on premarital sexual behavior on multiple sexual partners in the past year, on temporary sexual partners in the past year, having commercial sexual experiences in the past year and ever used condoms when engaging in casual sex, were 6.4% (60/366), 18.0%(66/366), 5.7%(21/366), 1.9%(7/366) and 8.0%(25/311), respectively. Conclusions: Few numbers of HIV infections were identified among the migrating workers with Derung minority, with sexual transmission as the major route, along with the increased number of rural migrant workers and the low rates both on AIDS knowledge and condom use, accompanied by the high risk sexual behavior appeared in this rural adult residents of Derung minority. Relative strategies on HIV/AIDS intervention and control should be developed.

The changing HIV-1 genetic characteristics and transmitted drug resistance among recently infected population in Yunnan, China.

Multiple human immunodeficiency virus (HIV)-1 genotypes in China were first discovered in Yunnan Province before disseminating throughout the country. As the HIV-1 epidemic continues to expand in Yunnan, genetic characteristics and transmitted drug resistance (TDR) should be further investigated among the recently infected population. Among 2828 HIV-positive samples newly reported in the first quarter of 2014, 347 were identified as recent infections with BED-captured enzyme immunoassay (CEIA). Of them, 291 were successfully genotyped and identified as circulating recombinant form (CRF)08_BC (47.4%), unique recombinant forms (URFs) (18.2%), CRF01_AE (15.8%), CRF07_BC (14.4%), subtype C (2.7%), CRF55_01B (0.7%), subtype B (0.3%) and CRF64_BC (0.3%). CRF08_BC and CRF01_AE were the predominant genotypes among heterosexual and homosexual infections, respectively. CRF08_BC, URFs, CRF01_AE and CRF07_BC expanded with higher prevalence in central and eastern Yunnan. The recent common ancestor of CRF01_AE, CRF07_BC and CRF08_BC dated back to 1983.1, 1992.1 and 1989.5, respectively. The effective population sizes (EPS) for CRF01_AE and CRF07_BC increased exponentially during 1991-1999 and 1994-1999, respectively. The EPS for CRF08_BC underwent two exponential growth phases in 1994-1998 and 2001-2002. Lastly, TDR-associated mutations were identified in 1.8% of individuals. These findings not only enhance our understanding of HIV-1 evolution in Yunnan but also have implications for vaccine design and patient management strategies.

[HIV-1 drug resistance transmission threshold survey in Dehong prefecture of Yunnan province, 2015].

Objective: To study the HIV-1 drug resistance transmission level in HIV infected persons receiving no antiviral therapy in Dehong prefecture of Yunnan province in 2015. Methods: A total of 72 plasma samples were collected from recently reported HIV-infected persons aged 16-25 years in Dehong from January to July 2015 for drug resistance gene detection. Results: Forty eight samples were successfully sequenced and analyzed. Among them, 31.2% (15/48) were from Chinese, and 68.8% (33/48) were from Burmese. Based on pol sequences, HIV genotypes included URF (52.08%, 25/48), CRF01_AE (16.67%, 8/48), RF07_BC (10.42%, 5/48), subtype B (6.25%, 3/48), subtype C (6.25%, 3/48), CRF57_BC (6.25%, 3/48) and CRF08_BC (2.08%, 1/48). One drug resistant mutation site to non-nucleoside analog reverse transcriptase inhibitor (NNRTI) and two drug resistant mutation site to nucleoside analog reverse transcriptase inhibitor (NRTI) were detected in four sequences. Based on the statistical method of HIV drug resistance threshold survey, the prevalence of HIV-1 drug resistant strain was 5%-15%. Conclusions: The proportion of Burmese among newly reported HIV-infected individuals aged 16-25 years in Dehong in 2015 was higher. HIV-1 genetic diversity was found in Dehong. The prevalence of HIV-1 drug resistant strain had reached a moderate level in Dehong.

[Effect of nasal glucocorticoid combined with loratadine or montelukast on allergic rhinitis].

Objective:To evaluate the effect of nasal glucocorticoid combined with second-generation antihistamines or leukotriene receptor antagonists on the treatment of moderate severe allergic rhinitis, and explore the optimal scheme of personalized treatment for AR patients.Method:Fiftyseven patients with persistent moderatesevere allergic rhinitis were randomly divided into three groups and treated by mometasone furoate aqueous nasal spray (group MOM), mometasone furoate aqueous nasal spray combined with loratadine (group MOM+L), mometasone furoate aqueous nasal spray combined with montelukast (group MOM+M) for 4 weeks. Four major clinical symptoms of allergic rhinitis: nasal congestion, nose itching, sneezing and runny nose were evaluated by "symptom rating score" before treatment and after treatment for 4 weeks.Result:After treatment, the total nasal symptom scores of each group showed a decreasing tendency, and the differences between various time points were statistically significant (P< 0.05). For the symptom of nasal congestion, the symptom score of MOM+M group was significantly lower than that of MOM group and MOM+L group at the 2nd and 4th week after treatment. For the symptoms of sneezing and nasal itching, MOM+L group had the lowest score at each time point after treatment and the difference was statistically significant compared with MOM group (P< 0.05), but there was no significant difference between MOM group and MOM+M group (P> 0.05). For the symptom of runny nose, the score of MOM+L group was significantly lower than MOM group (P< 0.05) at the 1st and 2nd week, MOM+M group was significantly lower than MOM group (P< 0.05) at the 2nd and 4th week, while there was no significant difference between MOM+L group and MOM+M group (P> 0.05).Conclusion:Nasal glucocorticoid alone or combined with secondgeneration antihistamines or leukotriene receptor antagonists can effectively control nasal symptoms of moderatesevere allergic rhinitis, yet the effect of combination therapy is better. For nasal congestion, nasal glucocorticoid combined with leukotriene receptor antagonists have a better effect. For nasal itching and sneezing, the choice of nasal glucocorticoid combined with second-generation antihistamines may be more sensible. For runny nose, nasal glucocorticoid combined with second-generation antihistamines or leukotriene receptor antagonists have similar efficacy.

[Evaluation of blood eosinophil in the diagnosis of eosinophilic chronic rhinosinusitis].

OBJECTIVE: To evaluate the practice of peripheral blood eosinophil in the diagnosis of eosinophilic chronic rhinosinusitis(ECRS). METHODS: The correlation between eosinophil count and percentage in peripheral blood and that in topic tissue in 787 patients (the first affiliated hospital of Wenzhou medical university, from Jan. 2013 to Jun. 2016) with chronic rhinosinusitis (CRS) were retrospectively analysed. The optimal cutoff value of blood eosinophil count and percentage as predictors for ECRS was determined by receiver operating characteristic curves (ROC) and their diagnostic ability was compared. RESULTS: The positive correlation between eosinophil count and percentage in blood and that in tissue was found respectively in 787 patients with CRS (r=0.450, 0.499, 0.463, 0.465, P<0.01). Although the significant correlation between blood eosinophil count and its count and percentage in tissue was not found after blood leukocyte and tissue eosinophilic inflammation was controlled respectively (r=0.041, P=0.380; r=0.046, P=0.329 and r=0.023, P=0.618; r=0.032, P=0.499), blood eosinophil percentage still showed significant correlation with tissue eosinophil count and percentage, but reduced unequally after that(r=0.383, 0.436 and r=0.153, 0.169, P<0.01). With ROC analysis, the diagnostic ability of optimal cut off values of eosinophil count and percentage varied as the histological criteria for ECRS differed. CONCLUSIONS: Eosinophil in peripheral blood showed significant positive correlation with its tissue infiltration, which may be not strong and easily effected by individual factors.Theoretically, blood eosinophil may have a diagnostic significance as a predictor for ECRS but not practically.

[HIV prevalence and risk factors among left-behind women in high HIV epidemic rural areas of Yunnan province].

OBJECTIVE: To understand the status of HIV infection and risk factors among those left-behind women (LBW) in high HIV epidemic rural areas. METHODS: A cross-sectional investigation was conducted between March and May, 2015 in Dehong and Lincang prefectures, Yunnan province, where HIV appeared highly epidemic. Probability Proportion to Size (PPS) sampling method was used, and 500 cases were involved and tested for HIV antibody. RESULTS: The total rate of HIV infection among LBW was 8.2% (41/500). The rate of HIV infection among LBWs whose husbands were on medication was 22.7% (30/132). Data from Multi-factor logistic regression analysis showed that the risk factors of HIV infection were: being minorities, education background lower than junior high school, widowed, living in Lincang prefecture, husband infected with HIV but did not consistently use condoms,etc. The rate of HIV infection among other LBWs was 2.8% (10/363). Data from Multi-factor logistic regression analysis showed that the risk factors of HIV infection would include: aged between 30-40 years, being minorities, education background lower than junior high school, divorced, living in Dehong prefecture, having had multiple-sex partners, husband coming home less than once a year,etc. The rate of HIV infection among drug users whose husbands did not take HIV medication was 20.0% (1/5). CONCLUSION: HIV prevalence among LBWs in highly HIV epidemic areas was high, and the major risk factors related to their husbands were: being drug users or with HIV infected. Further effort should be made on consistently use of anti-HIV drugs and prevention of inter-marital sexual transmission. Comprehensive intervention should be carried out for LBWs who were having lower education background, being minority and having multiple-sex partners.

[Study on the threshold of HIV-1 drug resistance in Dehong prefecture of Yunnan province in 2014].

OBJECTIVE: To study the HIV-1 genotypes and transmitted drug resistance (TDR) in Dehong prefecture of Yunnan province in 2014. METHODS: A total of 70 plasma samples of recently reported HIV-infected individuals between 16 and 25 years old were collected in Dehong prefecture from January to August 2014. Among them, 58 samples which met the criterion of HIV drug resistance threshold survey (HIVDR-TS) were subjected to genetic drug resistance detection. RESULTS: 50 plasma samples were successfully sequenced and analyzed. Among them, 34.0% were Chinese and 66.0% were Burmese. Based on pol sequences, all the identified HIV genotypes would include CRF01_AE (28.0%), subtype C(20.0%), URF(20.0% ), CRF62_BC(10.0% ), CRF08_BC(8.0% ), CRF07_BC (4.0%), CRF64_BC(4.0%), subtype B(4.0%) and CRF55_01B(2.0%). One drug, which resistant mutation to proteinase inhibitors had been detected in one sequence. Based on the statistical method of HIVDR-TS, the prevalence of transmitted HIV-1 drug resistance was adjusted as <5%. CONCLUSION: The proportion of Burmese was relatively higher among those newly reported HIV-infected individuals aged 16 to 25 in Dehong. We noticed that the novel circulating recombinant forms began to function. However, the level of transmission through HIV-1 drug resistant strains still kept low in Dehong.

Characterization of Rice Blast Resistance Gene Pi61(t) in Rice Germplasm.

Identification of resistance (R) genes to races of Magnaporthe oryzae in rice (Oryza sativa) germplasm is essential for the development of rice cultivars with long-lasting blast resistance. In the present study, one major quantitative trait locus, qPi93-3, was fine mapped using a recombinant inbred line (RIL), F8 RIL171, derived from the cross between 'Nipponbare' and '93-11'. RIL171 contained a heterozygous qPi93-3 allele which was found to be resistant against nine U.S. common races-ID1, IA1, IB49, IE1, IA45, IB1, IC17, IB45, and IH1-of M. oryzae. An F2 mapping population consisting of 2,381 individuals derived from RIL171 was evaluated with a field isolate (race) ARB82 (IA1) of M. oryzae under greenhouse conditions. Disease reaction of a resistant/susceptible ratio of 3:1 was identified with F2:F3 families. In total, 12 simple sequence repeat markers spanning qPi93-3 were used for fine mapping. Consequently, qPi93-3 was delimited to 4.2 Mb between RM3246 and RM7102. Three insertion-deletion (InDel) markers located between RM3246 and RM7102, that had previously used to map Pi61(t), showed that qPi93-3 was Pi61(t). The existence of Pi61(t) in 136 rice germplasm lines from the United States Department of Agriculture rice core collection was evaluated using Pi61(t)-specific InDel markers. Pi61(t) was identified as a source of resistance in 5 of the 136 lines. The characterized germplasm will be useful for rice breeders to use for improving blast resistance.

Update on diversity and distribution of HIV-1 subtypes in Yunnan province.

The aim of this study was to characterize updated HIV subtypes in Yunnan to determine their origins and distribution within the population. RT-PCR of both the gag and env genes were sequenced from Yunnan province inhabitants newly diagnosed with HIV-1. Sequence data from 290 samples were used for statistical analysis of subtype distribution and phylogenetic tree construction. Distribution data were adjusted to account for different geographical distributions of HIV-1 subtypes in the population. Phylogenetic analysis revealed six HIV-1 subtypes in Yunnan, including eight types of unique recombination forms (URFs). The most prevalent subtypes in this province, CRF07_BC (18·9%), CRF08_BC (39·1%), CRF01_AE (22·4%), and URFs (subtype C, 5·9% and subtype B, 4·5%), were all recombinants. We found significant differences in the distribution of these HIV-1 subtypes not only geographically, but also between various ethnic groups and with respect to transmission routes. Our findings indicate a complex population of HIV-1 subtypes, URFs, and recombinant subtypes in Yunnan province. This diversity could make the prevention and control of HIV infection in Yunnan more difficult due to the possibility of virus recombination or infection by multiple subtypes.

Identification of the rice blast resistance gene Pib in the National Small Grains Collection.

The Pib gene in rice confers resistance to a wide range of races of the rice blast pathogen, Magnaporthe oryzae, including race IE1k that overcomes Pita, another broad-spectrum resistance gene. In this study, the presence of Pib was determined in 164 rice germplasm accessions from a core subset of the National Small Grains Collection utilizing DNA markers and pathogenicity assays. The presence of Pib was evaluated with two simple sequence repeat (SSR) markers and a dominant marker (Pib-dom) derived from the Pib gene sequence. Pathogenicity assays using two avirulent races (IE1k and IB1) and a virulent race (IB54) were performed to verify the resistance responses of accessions. Of the 164 accessions evaluated, 109 contained the Pib gene as determined using both SSR markers and pathogenicity assays, albeit different haplotypes were detected. The remaining 52 germplasm accessions were different in their responses to the blast races IB54, IE1k, and IB1, thus indicating the presence of R gene(s) other than Pib. The accessions characterized in this study could be used for marker-assisted breeding to improve blast resistance in indica and japonica cultivars worldwide.

Global expression profiling of yeast treated with an inhibitor of amino acid biosynthesis, sulfometuron methyl.

The expression pattern of 1,529 yeast genes in response to sulfometuron methyl (SM) was analyzed by DNA microarray technology. SM, a potent herbicide, inhibits acetolactate synthase, a branched-chain amino acid biosynthetic enzyme. Exposure of yeast cells to 0.2 microg/ml SM resulted in 40% growth inhibition, a Gcn4p-mediated induction of genes involved in amino acid and cofactor biosynthesis, and starvation response. The accumulation of intermediates led to the induction of stress response genes and the repression of genes involved in carbohydrate metabolism, nucleotide biosynthesis, and sulfur assimilation. Extended exposure to SM led to a relaxation of the initial response and induction of sugar transporter and ergosterol biosynthetic genes, as well as repression of histone and lipid metabolic genes. Exposure to 5 microg/ml SM resulted in >98% growth inhibition and stimulated a similar initial expression change, but with no relaxation after extended exposure. Instead, more stress response and DNA damage repair genes become induced, suggesting a serious cellular consequence. Other salient features of metabolic regulation, such as the coordinated expression of cofactor biosynthetic genes with amino acid biosynthetic ones, were evident from our data. A potential link between SM sensitivity and ergosterol metabolism was uncovered by expression profiling and confirmed by genetic analysis.

Portable fiber-optic immunosensor for detection of methsulfuron methyl.

This fiber optic sensor, based on competitive immunoreactions between coating-haptens and free haptens in solutions with corresponding antibodies, was developed to determine the concentration of the free hapten, methsulfuron-methyl. The ovalbumin (OVA)-methsulfuron-methyl conjugate was immobilized on a microscope slide. Horseradish peroxidase (HRP) labeled goat anti-rabbit IgG was used to generate an optical signal. The portable optical device consisted of a 0.25-W tungsten-halogen light source and a photosensitive diode detector. A typical competitive-binding calibration curve was seen between 0.3 and 100 ng/ml of methsulfuron-methyl. The detection limit for methsulfuron-methyl was 0.1 ng/ml.

Purification of functional active epidermal Langerhans cells: a simple and efficient new technique.

Our knowledge of the functional activity of the epidermal Langerhans cell has been severely hampered by the lack of an easy method of purification of these cells that is both efficient and reproducible. In the present study we have used immunomagnetic beads directly conjugated to an IgM class mouse anti-human human leukocyte antigen DR monoclonal antibody to positively select human Langerhans cells from an epidermal cell suspension. Cells were then treated with a high-affinity polyclonal anti-mouse immunoglobulin that detached the beads by competing with the antigen for the antigen-binding site on the monoclonal antibody. This procedure allowed removal of the immunomagnetic beads, leaving Langerhans cells free from bound antibody. Recovery of Langerhans cells ranged from 40 to 80% of the starting number of Langerhans cells. The resulting cells were up to 99% CD1a positive and showed potent functional activity in the allogeneic mixed epidermal cell - lymphocyte reaction. Keratinocytes were shown to exert a profound inhibitory effect on Langerhans cell function that could not be prevented by indomethacin. This method is technically simple and allows good recovery of a highly purified population of Langerhans cells that are functionally active.