Nano titanium dioxide induces the generation of ROS and potential damage in HaCaT cells under UVA irradiation

Nano titanium dioxide (nano-TiO2) is frequently used in cosmetics, especially in sunscreen. Nano-TiO2 has been reported to be an efficient photocatalyst, which is able to produce reactive oxygen species (ROS) under UVA irradiation. However, the effects and mechanisms of skin toxicity caused by nano-TiO2 remain unclear. In this study, we explored the cytotoxicity and oxidative stress induced by nano-TiO2 under UVA irradiation with different crystal forms (anatase, rutile and anatase/rutile) and sizes (4 nm, 10 nm, 21 nm, 25 nm, 60 nm) in human keratinocyte HaCaT cells. Intracellular distribution of nano-TiO2, cell viability, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), super oxide dismutase (SOD) activity and Malondialdehyde (MDA) content were measured. The results showed that nano-TiO2 (10-200 microg/ml) significantly reduced cell viability in a dose-dependent manner in HaCaT cells. The cell viability was 76.9%, 60.2%, and 44.1% following nano-TiO2 (4 nm), nano-TiO2 (10 nm) and P25 treatment at the concentration of 200 microg/ml, respectively (P < 0.01). Nano-TiO2 induced ROS resulted in oxidative stress in these cells by reducing SOD and increasing MDA levels. The MMP of the cells was decreased significantly (P < 0.01) while the apoptosis rate was increased. Anatase and amorphous forms of nano-TiO2 showed higher cytotoxicity than the rutile form. The results indicated that nano-TiO2 could induce the generation of ROS and damage HaCaT cells under UVA irradiation.

Lactoferrin-derived peptides and Lactoferricin chimera inhibit virulence factor production and biofilm formation in Pseudomonas aeruginosa

AIMS

To investigate the bactericidal activity of lactoferrin-derived peptides and a new LF-derived peptides chimera (LFchimera) against P. aeruginosa and the influence on virulence factors of P. aeruginosa.

METHODS AND RESULTS

Lactoferricin (LFcin) and lactoferrampin (LFampin) are highly bioactive peptides isolated from the N-terminal region of lactoferrin (LF) by pepsin digestion. In this study, we designed LFchimera containing LFcin amino acids 17-30 and LFampin amino acids 268-284. Pseudomonas aeruginosa cells were incubated in medium with peptides at different concentrations, and then the assays of viability, pyocyanin, elastase activity and biofilm formation of P. aeruginosa were performed. We found that the concentration-dependent antibactericidal activity and down-regulating pyocyanin, elastase and biofilm formation of LFchimera were significantly stronger than those of LF, LFcin, LFampin or LFcin plus LFampin.

CONCLUSIONS

Our results indicated that LF, LFcin, LFampin and LFchimera were potential candidates to combat P. aeruginosa, and LFchimera was the most effective in them.

SIGNIFICANCE AND IMPACT OF THE STUDY

The new LFchimera has better activity against P. aeruginosa than LF, LFcin and LFampin and may be a promising new compound for treatment of P. aeruginosa infection.

Inactivation of AMPK alters gene expression and promotes growth of prostate cancer cells

AMP-activated protein kinase (AMPK) serves as a fuel-sensing enzyme that is activated by binding of AMP and subsequent phophorylation by upstream kinases such as the tumor suppressor LKB1, when cells sense an increase in the ratio of AMP to ATP. Acute activation of AMPK stimulates fatty acid oxidation to generate more ATP and simultaneously inhibits ATP-consuming processes including fatty acid and protein syntheses, thereby preserving energy for acute cell surviving program, while the chronic activation leads to inhibition of cell growth. The goal of the present study is to explore the mechanisms by which AMPK regulates cell growth. Toward this end, we established stable cell lines by introducing a dominant negative mutant of AMPK α1 subunit or its shRNA into the prostate cancer C4-2 cells and other cells, or wild type LKB1 into the lung adenocarcinoma A549 and breast MB-MDA-231 cancer cells, both of which lack functional LKB1. Our results showed that the inhibition of AMPK accelerated cell proliferation and promoted malignant behavior such as increased cell migration and anchorage-independent growth. This was associated with decreased G1 population, downregulation of p53 and p21, and upregulation of S6K, IGF-1 and IGF1R. Conversely, treatment of the C4-2 cells with 5-aminoimidazole-4-carboxamide 1-Dribonucleoside (AICAR), a prototypical AMPK activator, caused opposite changes. In addition, our study using microarray and RT-PCR revealed that AMPK regulated gene expression involved in tumor cell growth and survival. Thus, our study provides novel insights into the mechanisms of AMPK action in cancer cells and presents AMPK as an ideal drug target for cancer therapy.

Compound heterozygosity for two novel mutations (1203insG/Y1456X) in the von Willebrand factor gene causing type 3 von Willebrand disease

A 23-year-old Chinese woman with severe von Willebrand factor (VWF) deficiency and her parents were investigated by PCR/direct sequencing of the VWF gene. The patient was found to be compound heterozygous for two novel null mutations. The first was a microinsertion in exon 8 (1203insG) that introduced a frameshift at codon 298 leading to premature translational termination at codon 302. The second was a C to A transversion in exon 28 which resulted in the replacement of tyrosine 562 by a stop codon (Y1456X). The failure to amplify VWF cDNA from the patient by semi-nested PCR is consistent with the induction of nonsense-mediated mRNA decay.

Phase I/II study of sequential-intermittent docetaxel (D) and imatinib (Im) in hormone refractory prostate cancer (HRPC) (NYU 04–47)

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Background: Platelet-derived growth factor (PDGF) is frequently expressed in advanced prostate cancer (PC) lesions where it supports PC cell growth and neo-angiogenesis. Im. is a PDGF inhibitor that blocks cell cycle progression in G1-S through inhibition of erk1–2 kinase. D. blocks cell cycle progression in G2-M. Anti-tumor responses can increase when the block to cell cycle progression in G2M precede the blocks in G1-S. This study was designed to determine tolerablity and activity of sequential D followed by Im in HRPC patients (pts). Methods: Eligibility: 2 prior hormone manipulations, any prior chemotherapy, PSA= 5 ng/ml, ECOG PS 0–2. Treatment schema: D IV day 1 followed in 24–36 hours by Im PO daily x 14 days, every 21 days until toxicity or progression. Cohorts (C) planned were: #1, D. 60 mg/m2, Im. 400 mg; #2, D 70mg/m2, Im 400 mg; #3, D 70mg/m2, Im 600 mg. Results: 12 pts enrolled: 6 in C#1, 3 each in C#2,3. Median age,73 (range: 61 to 85). Median number cycles (Cy) 3 (range: 2 to 10). Toxicity grade (TG)1–2 observed in 9 (75%) pts (6, 2, 1 in C#1, 2,3 respectively): anemia 9, neutropenia 1, lymphopenia 6, thrombocytopenia 3, hyperglycemia 8, hyponatremia 2, abnormal bicarbonate 7, hypoalbuminemia 3, fatigue 5, neuropathy 3, nausea/vomiting 3, constipation 2, pain 2, fever 2, increased creatinine 2. TG3: afebrile neutropenia, 4 pts. Cy1. TG 4: febrile neutropenia,1 pt C#1,Cy1; GI bleed/intestinal perforation, 1 pt C#3, Cy7. PSA decline =50%: 1 pt C#2; 2 pts C#3. Conclusions: sequential and intermittent dosing of D and Im was well tolerated with high doses of both drugs. The most common toxicity was neutropenia which was prevented with growth factors. The MTD was not reached. PSA responses occurred at the higher doses. An ongoing phase II study of sequential D. 70mg/m2 and Im. 600 mg x 14 days will define activity.

No significant financial relationships to disclose.

Molecular diagnostics in China

Molecular diagnostics is changing the face of clinical laboratories and laboratory medicine. The case of China is no exception. In the present paper, a brief description on this promising discipline is given first, followed by an overview of the development of molecular diagnostics in China. Work done in the author's own laboratory is introduced in the third part and a short discussion on the challenges ahead is provided last.

Inverse adaptive cluster sampling

Consider a population in which the variable of interest tends to be at or near zero for many of the population units but a subgroup exhibits values distinctly different from zero. Such a population can be described as rare in the sense that the proportion of elements having nonzero values is very small. Obtaining an estimate of a population parameter such as the mean or total that is nonzero is difficult under classical fixed sample-size designs since there is a reasonable probability that a fixed sample size will yield all zeroes. We consider inverse sampling designs that use stopping rules based on the number of rare units observed in the sample. We look at two stopping rules in detail and derive unbiased estimators of the population total. The estimators do not rely on knowing what proportion of the population exhibit the rare trait but instead use an estimated value. Hence, the estimators are similar to those developed for poststratification sampling designs. We also incorporate adaptive cluster sampling into the sampling design to allow for the case where the rare elements tend to cluster within the population in some manner. The formulas for the variances of the estimators do not allow direct analytic comparison of the efficiency of the various designs and stopping rules, so we provide the results of a small simulation study to obtain some insight into the differences among the stopping rules and sampling approaches. The results indicate that a modified stopping rule that incorporates an adaptive sampling component and utilizes an initial random sample of fixed size is the best in the sense of having the smallest variance.

A novel growth suppressor gene on chromosome 17p13.3 with a high frequency of mutation in human hepatocellular carcinoma

Previous studies have shown that there is a high frequency of loss of heterozygosity (LOH) on chromosome 17p13.3 in hepatocellular carcinoma [HCC (M. Fujimori et al., Cancer Res., 51: 89-93, 1991; H. Nagai et al., Oncogene, 14: 2927-2933, 1997; V. Boige et al., Cancer Res., 57: 1986-1990, 1997; Z. Piao et al., Int. J. Cancer, 75: 29-33, 1998; and B. Charroux et al., J. Cell Biol., 148: 1177-1186, 2000)]. The minimum region of LOH on chromosome 17p13.3 in HCC has been defined within the region between D17S643 and D17S1574. Moreover, D17S926 in the minimum region of LOH has the highest frequency of LOH, and its sequencing analysis has been accomplished. In this region, 6 of 13 novel genes have been characterized (X. Zhao, D. Wan, M. He, Yu. Ye, Yi. He, L. Han, M. Guo, Y. Huang, W. Qin, M-W. Wang, W. Chong, J. Chen, L. Zhang, N. Yang, B. Xu, M. Wu, L. Zuo, and J. Gu. A high frequency LOH region on chromosome 17p13.3 in human HCC with densely clustered genes identified, submitted for publication). Here we describe the cloning and characterization of one of these novel genes, designated HCC suppressor 1 (HCCS1), located at this region. HCCS1 had 18 exons, and its full-length cDNA was 2.0 kb. The protein expression product of HCCS1 was located in mitochondria. HCCS1 had a high frequency of mutations in HCC samples, whereas no alteration has been found in matched noncancerous liver tissues. Immunohistochemistry revealed a significantly higher expression of HCCS1 in the noncancerous liver tissues (33 of 35 samples) than in the HCC samples (2 of 35 samples). Transfection of HCCS1 cDNA into the HCC cell line remarkably reduced the efficiency of its colony formation and inhibited tumor growth in nude mice. Taken together, these findings strongly suggest a potential role of HCCS1 as a HCC putative suppressor gene.

Predominance of NK1.1+TCR alpha beta+ or DX5+TCR alpha beta+ T cells in mice conditioned with fractionated lymphoid irradiation protects against graft-versus-host disease: "natural suppressor" cells

We developed a nonmyeloablative host conditioning regimen in a mouse model of MHC-mismatched bone marrow transplantation that not only reduces radiation toxicity, but also protects against graft-vs-host disease. The regimen of fractionated irradiation directed to the lymphoid tissues and depletive anti-T cell Abs results in a marked change in the residual host T cells, such that NK1.1+ or DX5+asialo-GM1+ T cells become the predominant T cell subset in the lymphoid tissues of C57BL/6 and BALB/c mice, respectively. The latter "natural suppressor" T cells protect hosts from graft-vs-host disease after the infusion of allogeneic bone marrow and peripheral blood cells that ordinarily kill hosts conditioned with sublethal or lethal total body irradiation. Protected hosts become stable mixed chimeras, but fail to show the early expansion and infiltration of donor T cells in the gut, liver, and blood associated with host tissue injury. Cytokine secretion and adoptive transfer studies using wild-type and IL-4(-/-) mice showed that protection afforded by NK1.1+ and DX5+asialo-GM1+ T cells derived from either donors or hosts conditioned with lymphoid irradiation is dependent on their secretion of high levels of IL-4.

Allogeneic bone marrow cells that facilitate complete chimerism and eliminate tumor cells express both CD8 and T-cell antigen receptor–αβ

Nonmyeloablative host conditioning regimens have been used in clinical allogeneic bone marrow and hematopoietic progenitor transplantation to effectively treat lymphohematopoietic tumors and reduce early toxicity. However, severe graft-versus-host disease (GVHD) remains a major problem. The goal of the current study was to determine whether specific subsets of cells in allogeneic bone marrow transplants can effectively treat the BCL1 B-cell lymphoma in nonmyeloablated BALB/c mouse hosts given a single dose of sublethal (450 cGy) total body irradiation, without inducing severe GVHD. The experimental results show that high doses of whole bone marrow cells from major histocompatiblity complex (MHC)-mismatched donors eliminate both normal and malignant host-type lymphohematopoietic cells without causing injury to nonlymphohematopoietic host tissues. The CD8+T-cell antigen receptor–αβ+(TCRαβ+) T cells within the marrow transplants mediated the killing of the tumor cells via both perforin- and FasL-dependent pathways. Cells present in marrow transplants from either CD8−/− or TCRα−/− donors failed to eliminate malignant and normal host lymphohematopoietic cells. Addition of small numbers of blood mononuclear cells to the marrow inoculum caused lethal GVHD. Thus, the resident allogeneic bone marrow CD8+ TCRαβ+ T cells had the unique capacity to eliminate the host lymphohematopoietic cells without nonlymphohematopoietic tissue injury.

Determination of concentration of cytosolic NADH-cytochrome b5 reductase in erythrocytes from normal Chinese adults, neonates and patients with hereditary methemoglobinemia by double-antibody sandwich ELISA

NADH-cytochrome b5 reductase (b5R), present in various tissues of the body, is a redox enzyme of multiple functions. The deficiency of the enzyme leads to hereditary methemoglobinemia. With rabbit anti-b5R antibody for plate coating and enzyme-labeled anti-b5R monoclonal antibody as reporter, we have developed a sandwich ELISA procedure for the determination of b5R concentration. This procedure is sensitive to a wide range of linearity, and convenient in coping with large numbers of samples. Using this novel method, cytosolic b5R concentration in the erythrocytes of 30 normal Chinese adults was estimated to be 25.63+/-8.54 ng/mg Hb. It was found that the concentration of red cell soluble b5R of five newborns was significantly lower than that of normal adults and soluble b5R was undetectable in the erythrocytes of 4 patients with type I hereditary methemoglobinemia. Our results demonstrated that the reduced b5R activity in red cell cytosol of both neonates and type I hereditary methemoglobinemic patients results largely or mainly from the lowered b5R concentration. Our novel method might be further exploited for in-depth investigation of the relationship between the qualitative and quantitative changes of b5R with regard to physiological and pathological conditions.

Cyclosporine facilitates chimeric and inhibits nonchimeric tolerance after posttransplant total lymphoid irradiation

BACKGROUND

Previous studies showed that Lewis rats given posttransplant total lymphoid irradiation, antithymocyte globulin, and a single infusion of ACI peripheral blood or bone marrow cells develop tolerance to ACI heart allografts.

METHODS

To determine the effects of cyclosporine on these tolerance induction protocols, groups of Lewis hosts, given either ACI blood or marrow infusions, were given a 60-day course of daily cyclosporine immediately after the cell infusion.

RESULTS

Cyclosporine treatment was associated with uniform graft rejection in the groups given an ACI blood transfusion, and was associated with uniform graft acceptance in the groups given an ACI bone marrow infusion. Studies of donor-type T and B cell chimerism in the host blood showed that cyclosporine facilitated chimerism in the hosts given ACI bone marrow cells, and stable chimerism over a 300-day observation period was predicted by detectable chimerism by day 30. None of the hosts given ACI blood cells developed chimerism.

CONCLUSION

Cyclosporine facilitated long-term graft acceptance in a tolerization protocol that induced mixed chimerism, but prevented long-term graft acceptance in a tolerization protocol that did not induce chimerism.

Separating favorable from unfavorable prognostic markers in breast cancer: the role of E-cadherin

Distant metastases are the major cause of morbidity and mortality in women with breast cancer. The ability to predict the metastatic proclivity is essential in choosing the optimal treatment. Tumor size and grade, which are frequently used markers in node-negative breast cancer patients, are inadequate markers for prognosis and individualized treatment design. The steps in metastatic progression include angiogenesis, invasion, and changes in adhesion characteristics. We developed a strategy for choosing biomarkers representing these steps in malignant progression to identify patients with occult metastases who will need chemotherapy and spare those women whose tumors have not developed the capacity to spread. To evaluate the added significance of E-cadherin to that of nm23-H1 and angiogenesis in determining metastatic proclivity, we used archival material from 168 node-negative breast cancer patients who were treated with mastectomy without any adjuvant chemotherapy or hormone therapy. Immunohistochemistry was used to detect E-cadherin and nm23-H1 expression, whereas angiogenesis was determined by microvessel count (MVC) after immunohistochemical staining. The median follow-up is 14 years. We found that E-cadherin is better in identifying the poor prognosis patients. The 14-year disease-free survival (DFS) is 84%, 80%, and 56% in patients with high, intermediate, and low E-cadherin. The worst prognosis group using nm23-H1 and MVC as biomarkers has a 14-year DFS of 62%. In this group, if E-cadherin is low, the 14-year DFS is further decreased to 44%. Nm23-H1 and MVC are better in identifying the good prognosis patients. The long-term DFS is >90% if MVC is low or if nm23-H1 is high. Multivariate analysis shows that E-cadherin, nm23-H1, and MVC are more significant prognostic biomarkers than tumor size or grade. Loss of E-cadherin appears to be a latter step in the metastatic progression compared to angiogenesis and the loss of nm23-H1 expression.

Periprosthetic bone remodelling around a prosthesis for distal femoral tumours

We used dual-energy x-ray absorptiometry (DEXA) to evaluate the extent of periprosthetic bone remodelling around a prosthesis for distal femoral reconstruction, the Kotz modular femoral tibial replacement (KMFTR; Howmedica, Rutherford, New Jersey). A total of 23 patients was entered into the study which had four parts: 1) 17 patients were scanned three times on both the implant and contralateral legs to determine whether the precision of DEXA measurements was adequate to estimate bone loss surrounding the anchorage piece of the KMFTR; 2) in 23 patients the bone mineral density (BMD) in different regions of interest surrounding the diaphyseal anchorage was compared with that of the contralateral femur at the same location to test whether there was consistent evidence of loss of BMD adjacent to the prosthetic stem; 3) in 12 patients sequential studies were performed about one year apart to compare bone loss; and 4) bone loss was compared in ten patients with implants fixed by three screws and in 13 without screws.

The mean coefficients of variation (SD/mean) for the 17 sets of repeated scans ranged from 2.9% to 7.8% at different regions of interest in the KMFTR leg and from 1.4% to 2.5% in the contralateral leg. BMD was decreased in the KMFTR leg relative to the contralateral limb and the percentage of BMD loss in general increased as the region of interest moved distally in the femur. Studies done after one year showed no consistent pattern of progressive bone loss between the two measurements. The ten patients with implants fixed by screws were found to have a mean loss of BMD of 42% in the most distal part of the femur, while the 13 without screw fixation had a mean loss of 11%.

DEXA was shown to have adequate precision to evaluate loss of BMD around the KMFTR. This was evident relative to the contralateral leg in all patients and generally increased in the most distal part of the femur. In general, it stabilised between two measurements taken one year apart and was greater surrounding implants fixed by cross-locking screws.

Periprosthetic bone remodelling around a prosthesis for distal femoral tumours. Measurement by dual-energy X-ray absorptiometry (DEXA)

We used dual-energy x-ray absorptiometry (DEXA) to evaluate the extent of periprosthetic bone remodelling around a prosthesis for distal femoral reconstruction, the Kotz modular femoral tibial replacement (KMFTR; Howmedica, Rutherford, New Jersey). A total of 23 patients was entered into the study which had four parts: 1) 17 patients were scanned three times on both the implant and contralateral legs to determine whether the precision of DEXA measurements was adequate to estimate bone loss surrounding the anchorage piece of the KMFTR; 2) in 23 patients the bone mineral density (BMD) in different regions of interest surrounding the diaphyseal anchorage was compared with that of the contralateral femur at the same location to test whether there was consistent evidence of loss of BMD adjacent to the prosthetic stem; 3) in 12 patients sequential studies were performed about one year apart to compare bone loss; and 4) bone loss was compared in ten patients with implants fixed by three screws and in 13 without screws. The mean coefficients of variation (SD/mean) for the 17 sets of repeated scans ranged from 2.9% to 7.8% at different regions of interest in the KMFTR leg and from 1.4% to 2.5% in the contralateral leg. BMD was decreased in the KMFTR leg relative to the contralateral limb and the percentage of BMD loss in general increased as the region of interest moved distally in the femur. Studies done after one year showed no consistent pattern of progressive bone loss between the two measurements. The ten patients with implants fixed by screws were found to have a mean loss of BMD of 42% in the most distal part of the femur, while the 13 without screw fixation had a mean loss of 11%. DEXA was shown to have adequate precision to evaluate loss of BMD around the KMFTR. This was evident relative to the contralateral leg in all patients and generally increased in the most distal part of the femur. In general, it stabilised between two measurements taken one year apart and was greater surrounding implants fixed by cross-locking screws.

Donor-type chimerism determination by competitive polymerase chain reaction (PCR) in a primate model for bone marrow transplantation

BACKGROUND

Evaluation of the outcome of successful bone marrow transplantation (BMT) and in-depth studies of transplantation biology rely increasingly on accurate detection of donor origin cells in the transplanted recipients. This study describes a quantitative competitive polymerase chain reaction (PCR) assay for accurate evaluation of chimerism after allogeneic BMT in a cynomologous primate model, based on detection of monkey Y-specific DNA.

METHODS

A competitor standard was generated via PCR using a mutagenic primer that makes the competitor DNA 22 bp less than the wild type monkey Y-specific DNA. The mutated form can still be amplified by the primer pair for the detection of monkey Y-specific DNA. A fixed amount of sample subjected to chimerism detection was co-amplified with a range of competitor DNA using a touch down program and hot start PCR technique. The PCR products were analyzed by computing densitometry. The ratio of competitor/target (Y-specific) DNA for each sample pair was calculated.

RESULTS

Using DNAs prepared from an artificial mixture of male and female cells, a set of standard curves has been obtained and the sensitivity of the established quantitative PCR was found to be 25 pg of male DNA, which corresponds approximately to 0.005 fg competitor DNA. A DNA sample taken from a female monkey, transplanted with purified CD34+ stem cells from a male monkey donor 26 days after BMT, was subjected to the competitive PCR with 10% male DNA as a control; the level of male DNA in this sample was calculated to be around 50%.

CONCLUSIONS

This quantitative PCR assay offers both a high degree of specificity as well as a very accurate and sensitive evaluation of chimerism in a sex-mismatched monkey BMT model.

Molecular mechanism of recessive congenital methemoglobinemia in Chinese pedigrees

OBJECTIVE

To investigate the molecular mechanism of recessive congenital methemoglobinemia (RCM) in Chinese and to establish a gene diagnostic method of polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP).

METHODS

Total RNA was isolated from the peripheral leukocytes of the propositus and b5R cDNA synthesized by reverse transcription-polymerase chain reaction (RT-PCR). The coding region of b5R cDNA was analyzed by sequencing of the RT-PCR products.

RESULTS

Both propositi A and B were found to be homozygotes for a G to A transition at codon 57 in exon 3, changing a guanine to an adenine. This point mutation was not an artificial occurrence during polymerase chain reaction (PCR), as confirmed by Msp I restriction enzyme analysis of the genomic DNA. Propositus A's mother and propositus B's sister and her nephew were found to be heterozygotes for the mutation.

CONCLUSION

A guanine-to-adenine transition at codon 57, replacing arginine with glutamine, was the molecular basis for RCM in two Chinese families.

Comparison of chimeric acid and non-chimeric tolerance using posttransplant total lymphoid irradiation: cytokine expression and chronic rejection

BACKGROUND

Previous studies showed that an intravenous infusion of donor blood cells facilitates tolerance to ACI heart allografts in Lewis rat hosts given posttransplant total lymphoid irradiation (TLI) and anti-thymocyte globulin (ATG). The object of the current study was to compare tolerance induction using donor cells that do or do not induce chimerism.

METHODS

Normal peripheral blood mononuclear cells (PBMC), granulocyte colony-stimulating factor (G-CSF)-mobilized PBMC, and bone marrow (BM) cells from ACI donors were tested for their capacity to prolong ACI heart allograft survival in Lewis hosts. Chimerism, anti-donor cell reactivity, and cytokine gene expression in grafts were determined.

RESULTS

Intravenous injections of equal numbers of all three donor cells markedly prolonged graft survival (median: >164 to >175 days) as compared to uninjected controls (median: 53 days). Chimerism among T and B cells in the blood was determined by immunofluorescent staining in hosts bearing long-term (> 150 days) grafts. Although no chimerism was detected in hosts given normal or G-CSF-mobilized PBMC, chimerism was detected at variable levels in all hosts given BM cells. Vigorous anti-donor reactivity in the mixed leukocyte reaction was present only in non-chimeric hosts. Long-term grafts from hosts given normal ACI PBMC developed chronic rejection, but those from hosts given ACI BM cells did not. The latter hosts showed the lowest levels of intragraft cytokine mRNA.

CONCLUSIONS

Chimeric tolerance is more robust than non-chimeric tolerance in the model of posttransplant TLI, ATG, and donor cell infusion, and is associated with less chronic rejection.

Bone marrow NK1.1(-) and NK1.1(+) T cells reciprocally regulate acute graft versus host disease

Sorted CD4(+) and CD8(+) T cells from the peripheral blood or bone marrow of donor C57BL/6 (H-2(b)) mice were tested for their capacity to induce graft-versus-host disease (GVHD) by injecting the cells, along with stringently T cell-depleted donor marrow cells, into lethally irradiated BALB/c (H-2(d)) host mice. The peripheral blood T cells were at least 30 times more potent than the marrow T cells in inducing lethal GVHD. As NK1.1(+) T cells represented <1% of all T cells in the blood and approximately 30% of T cells in the marrow, the capacity of sorted marrow NK1.1(-) CD4(+) and CD8(+) T cells to induce GVHD was tested. The latter cells had markedly increased potency, and adding back marrow NK1.1(+) T cells suppressed GVHD. The marrow NK1.1(+) T cells secreted high levels of both interferon gamma (IFN-gamma) and interleukin 4 (IL-4), and the NK1.1(-) T cells secreted high levels of IFN-gamma with little IL-4. Marrow NK1.1(+) T cells obtained from IL-4(-/-) rather than wild-type C57BL/6 donors not only failed to prevent GVHD but actually increased its severity. Together, these results demonstrate that GVHD is reciprocally regulated by the NK1.1(-) and NK1.1(+) T cell subsets via their differential production of cytokines.

Extended fitness of variable region primers by a novel PCR protocol

In an attempt to isolate the variable region genes of five monoclonal natural autoantibodies, we failed to amplify all ten variable region cDNAs using a V region primer set and following conventional PCR protocols. A novel PCR procedure was established in which the reaction began with three cycles of low temperature annealing and chain extension using 5'-primer as the only primer present, and continuing with conventional PCR cycles following addition of 3'-primer. Combined with solid-phase cDNA synthesis on oligo(dT)cellulose, this new protocol rescued all failed PCR amplifications based on a conventional protocol, thereby extending the universal utility of the V region primers. A notable increase in amplification specificity was also achieved. Such a protocol could be useful in primer design and the amplification of non-antibody genes whose sequences are not well-understood.