Corrected Panel-Reactive Antibody Positivity Rates for Hypersensitized Patients in Turkish Population With Calculated Panel-Reactive Antibody Software

INTRODUCTION

High rates of panel-reactive antibody (PRA) may decrease the chance of kidney transplantation and may result in long waiting periods before transplantation. The calculated PRA (cPRA) is performed based on unacceptable HLA antigens. These antigens are identified by a program that was created based on the antibodies that developed against the HLA antigens circulating in serum and on the risk of binding of these antibodies to antigens. The antigen profile of the population and antigen frequencies can be measured, and more realistic cPRA positivity rates may be obtained using this method.

MATERIALS AND METHODS

We developed a program based on the HLA antigens of 494 blood donors in 2 European Federation for Immunogenetics-accredited Tissue Typing Laboratories in Turkey. Next-generation sequencing-based tissue typing (HLA-A, -B, -C, -DR, -DQ, 4 digits) of the samples was performed. The PRA screening test was performed on 380 patients who were waiting for organ transplant from a cadaver in Istanbul Faculty of Medicine. The single antigen bead assay testing was performed to identify the antibody profiles on 48 hypersensitized patients.

RESULTS

The PRA testing results using the current methods were 44.6% ± 18.5%, and the cPRA rate was 86.2% ± 5.1%. The mean PRA positivity of the sensitized patients using the current methods was 44.6%; however, the rate was 86.2% using the cPRA.

DISCUSSION

cPRA shows the rate of the rejected donors according to all unacceptable antigens. The need for a list of unacceptable antigens in place of the PRA positivity rate is a real change in the sensitization-dependent calculation as cPRA positivity rate.

CONCLUSION

In principal, implementation of cPRA will encourage many centers and laboratories to adopt a standard measurement of sensitization in Turkey. It will increase the chances of better donor match, particularly for hypersensitized patients, by the creation of an unacceptable mismatch program using cPRA software.

Analysis of the Humoral Immune Response to Human Leukocyte Antigens in Turkish Renal Transplant Candidates and Relationship Between Autoimmune Disorders

BACKGROUND

Pre-transplant sensitization to human leukocyte antigens (HLA) is a risk factor for graft failure. The purpose of the current single-center study was to evaluate humoral immune response to HLA antigens and the possible relationship between anti-HLA antibody titer and autoimmune disorders in renal transplant candidates.

METHODS

A total of 435 renal transplant candidates were analyzed; 50 sensitized patients were enrolled in this study. The HLA typing was performed by use of enzyme-linked immunoassay combined with Luminex technology. The patients were questioned for clinical evidence of hypothyroidism and systemic lupus erythematosus (SLE) and investigated for anti-nuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA), anti-thyroglobulin (anti-TG), anti-thyroid peroxidase (anti-TPO) antibodies, and thyroid function tests.

RESULTS

Among 50 patients with positive panel reactive antibody, 24 (48%) were positive for class I and negative for class II, 12 (24%) were negative for class I and positive for class II, and 14 (28%) were positive for both classes I and II. The specificities of anti-HLA antibodies-A23, A68, A69, B27, B49, DR6, and DR8-were the most frequent. ANA and anti-dsDNA antibodies were not correlated with either clinical symptoms of SLE or anti-HLA antibody titer of renal transplant candidates. Similarly, anti-TG and anti-TPO antibodies were not correlated with clinical hypothyroidism or anti-HLA antibody titer.

CONCLUSIONS

Our data have demonstrated the profile of anti-HLA antibodies in patients who were on the renal transplant waiting list in Turkey. The most frequent specificities of anti-HLA antibodies were A23, A68, A69, B27, B49, DR6, and DR8. There was no association between anti-HLA antibody titer and clinical and laboratory evidence of SLE and hypothyroidism.

Is flow cytometry crossmatch analysis using sera with different dilutions important for pretransplant analysis? A case report

The most effective form of treatment for chronic renal failure is kidney transplantation from a cadaver or a living donor. For a kidney transplant to be successful, tissue compatibility and a lack of donor-specific anti-human leukocyte antigen (HLA) antibodies in the circulation of the patient are vital, in addition to ABO blood group compatibility. The presence of anti-HLA antibodies is assayed before transplantation using various methods, but because organ rejections have been observed in previous studies, different techniques are required to detect anti-HLA antibodies. Today, flow cytometry crossmatching is one of the most important and effective techniques in testing for donor-specific anti-HLA antibodies (DSAs). If weakly positive serum is assayed after serial dilution, it can yield high positivity. Herein, we describe the differences between the results for diluted and undiluted weakly positive sera studied using the flow cytometry crossmatch (FCXM) technique. In a recent study, the sera of weakly FCXM-positive patients were diluted 1/50, and the FCXM test was repeated. The use of diluted serum eliminated the effect of the prozone so that the DSAs could be detected.

'Immunogenetics of Aging': report on the activities of the 15th International HLA and Immunogenetics Working Group and 15th International HLA and Immunogenetics Workshop

'Immunogenetics of Aging' is a component that was first included in the 14th International HLA and Immunogenetics Workshop (IHIWS) and developed further within the 15th Workshop. The aim of this component was to assess the impact of human leukocyte antigen (HLA) genes, cytokine genes, and some innate immunity genes such as killer-cell immunoglobulin-like receptors (KIRs) and mannose-binding lectin 2 (MBL2) in successful aging and their contribution to the better understanding of immune dysfunction in old age. Within the 15th IHIWS new populations were included in the analysis. Additional cytokine gene polymorphisms were assessed and innate immunity genes were analyzed for possible relevance in longevity. The results showed that longevity might be associated with anti-inflammatory cytokine gene profiles, decreased frequency of interleukin-10 (IL-10) and transforming growth factor-B1 haplotypes associated with a low level of gene expression, and increased frequency of haplotypes determining a high level of expression. Extended tumor necrosis factor-A and IL-12B genotypes were also likely relevant to longevity. Data also showed that innate immunity genes are associated with susceptibility to infections in the elderly and showed that these genes might be an important genetic marker in aging. Decreased frequencies of KIR2DS5 and A1B10 haplotypes, and an increased proportion of MBL2-deficient haplotypes were found in the group with higher cytomegalovirus-specific IgG antibody levels. Together, these studies emphasize the relevance of genes regulating immune functions in maintaining human longevity and stress the importance of further clarifying their impact on successful aging.

Flow cytometric crossmatching and panel-reactive antibodies in chronic renal failure patients

AIM

Anti-donor antibodies, denoted as "panel-reactive antibodies" (PRAs), are one of the most important factors influencing graft survival after renal transplantation. PRA is generally analyzed with enzyme-linked immunosorbent assay or flow cytometry (FC), which identify the HLA antigen specific for the preformed antibody.

PATIENTS AND METHODS

We tested 66 patients for FC crossmatch (FCXM) when they were called for cadaveric renal transplantation. Thirty of 66 patients were FCXM-positive; 36 were FCXM-negative. Among the FCXM positive crossmatches, 21 were T- and B-cell positive; seven B positive; and two T positive. The HLA antibodies in the sera of FCXM-positive patients were reanalyzed using flow-PRA.

RESULTS

We detected HLA antibodies in 28/66 sera with flow PRA. The sera of 16/21 T-/B-, FCXM-positive patients contained both class I and II anti-HLA antibodies, five had only class I anti-HLA antibodies. One out of seven B-cell FCXM-positive patients had class I and class II anti-HLA antibodies, three, class I and 1 class II anti-HLA antibodies; the other two were negative. Class I and class II HLA antibodies were observed in two T-cell FCXM-positive patients. Four of 36 patients who were FCXM-negative were flow PRA positive: one had both class I and class II HLA antibodies and three, only class I HLA antibody. The comparison of FCXM and flow PRA results was significant (P = .001).

CONCLUSION

FCXM results may be confirmed by flow PRA tests, an important method to differentiate HLA versus non-HLA antibodies.

The frequency of HLA class I and II alleles in Turkish childhood acute leukaemia patients

In this study, blood samples were taken from 200 patients with childhood acute leukaemias, including acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML), and from 100 healthy volunteers (controls). The frequency of the human leucocyte antigen (HLA)-DRB1*04 allele was significantly higher, and the frequencies of the HLA-A23 and HLA-B7 antigens were significantly lower, in patients with ALL compared with controls. Among patients with AML, the frequency of the HLA-B49 antigen and the HLA-DRB1*15 allele were significantly higher, whereas the frequencies of the HLA-A11 and HLA-B38 antigens were significantly lower compared with controls. The frequency of the HLA-DRB1*04 allele was also significantly higher in male patients with ALL and AML, whereas the HLA-DRB1*13 allele was found significantly less frequently in male AML and female ALL patients than in controls. To date, this is the only study to evaluate the associations between HLA molecules and leukaemia in a Turkish population with acute childhood leukaemia.

FISH detection of chimerism in pediatric hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is a well-established curative therapy for various malignant and non-malignant diseases. Successful outcome after allogeneic HSCT has been associated with donor chimerism (DC). However, the detection of residual host cells or mixed hemopoietic chimerism (MC) has indicated that donor chimerism is not obligatory following HSCT. More recently, fluorescence in situ hybridization (FISH) analysis has been applied to engraftment studies for the identification of polymorphic or sex chromosomes. In this study, chimerism status was evaluated in 48 sex-mismatched HSCT pediatric patients (17 women/31 men, mean age: 9.02 +/- 3.95 years, range: 2-19) by FISH and the effect of DC or MC on outcome and long-term disease-free survival was documented. The stem cell source was bone marrow in all cases. All of the donors were human leucocyte antigen-identical siblings. FISH was performed on 156 specimens between days +13 and +1878. Donor chimerism was found in 47.9% (23/48) and MC was found in 52.1% (25/48) of the patients. Fifteen of 48 (31.25%) patients died, of whom 12 (80%) were MC and three patients (20%) were DC. The difference in chimerism status (MC or DC) was statistically significant between those patients who died and those still alive (chi(2) = 6.813; P = 0.009).

14th International HLA and Immunogenetics Workshop: report on the immunogenetics of aging

The 'Immunogenetics of Aging' is a newly included component within the 14th International HLA and Immunogenetics Workshop. The aim of this component was to determine the contribution of human leukocyte antigen (HLA), cytokine genes and other major histocompatibility complex-encoded loci to successful aging and to determine an increased capacity to reach the extreme limits of life span. Two main data sets from four European populations were included in this study: unrelated healthy elderly individuals and ethnically matched young controls, and families with longevity members. Analysis was focused on HLA class I and II and cytokine gene polymorphisms. Preliminary results showed increased frequencies of DRB1*11- and DRB*16-associated haplotypes that were found to be protective for autoimmune diseases in some populations. Additionally, in families with longevity members, alleles and haplotypes positively associated with autoimmunity were not observed. Analysis of cytokine gene polymorphisms showed prevalence of anti-inflammatory profiles in healthy elderly individuals. Inheritance of extended haplotypes in families with longevity members allowed the identification of immunogenetic profiles that could be predictive for longevity. These preliminary studies indicate the relevance of genes regulating immune functions in human longevity and the importance of clarifying further their impact in successful aging.

14th International HLA and Immunogenetics Workshop: Report from the reproductive immunology component

The aim of the study was to investigate whether human leukocyte antigen (HLA) allele sharing between partners or the maternal killer immunoglobulin-like receptor (KIR) repertoire is associated with recurrent spontaneous abortion (RSA) and repeated implantation failure after in vitro fertilization (IVF)/embryo transfer. From a total population of 158 RSA couples, 40 couples with repeated implantation failures (IVF) and 81 control couples, reported by five different laboratories, analysis was performed for (a) HLA sharing in 50 RSA, 31 IVF and 31 control couples, (b) DQA1*0505 sharing/homozygosity among partners in 108 RSA, 40 IVF and 36 control couples, and (c) the women's KIR repertoire in 46 RSA, 26 IVF and 36 control wives. RSA couples were divided into alloimmune aborter (RSAallo) and autoimmune aborter (RSAauto). The results oppose to the suggestion that increased HLA sharing per se or a limited maternal KIR repertoire predisposes to RSA or IVF failure. However, the observation of a slightly higher percentage of DQA1*0505 sharing in the RSAauto and the IVF group needs further investigation. The ratio of inhibitory to activating KIR (actKIR) was slightly lower in RSAallo and IVF women (1.9 vs 2.6 in controls), while in a high percentage of these women, the standard receptors of the KIR A haplotype were combined with actKIR/s of the haplotype B (66.6% and 45.4% vs 20% and 15.3% in RSAauto and control groups). This may suggest a possible involvement of actKIRs in embryo implantation and the maintenance of pregnancy and also requires further investigation.

HLA-DRB1*03 is a susceptibility gene in patients with Graves' disease with and without ophthalmopathy

We sought an association between certain human leucocyte antigen (HLA) markers and Graves' disease (GD) with and without ophthalmopathy (OP). One hundred and thirty-one Turkish patients with GD (50 without OP, 81 with OP) and 250 local healthy controls were studied. HLA-DRB1 typing was performed by using polymerase chain reaction-sequence-specific primers (PCR-SSP) method. The frequencies of DRB1*03 was significantly increased in GD compared to controls (OR = 2.07; 95% CI = 1.24-3.44), whereas DRB1*13 (OR = 0.33; 95% CI = 0.18-0.61) and DRB1*07 (OR = 0.31; 95% CI = 0.13-0.70) were significantly increased in controls compared to patients. None of the three associations showed any specificity to the OP group.

The role of HLA molecules in susceptibility to chronic rheumatic heart disease

Only a small fraction of the streptococcal pharyngitis progress to rheumatic carditis, which implies that environmental, host and microbial factors interact to cause an aberrant immune response against the antigens of the microorganism that cross-react with cardiac tissues. Although there are numerous studies and a general consensus on the relation between human leucocyte antigen (HLA) class II antigens and rheumatic heart disease (RHD), the details and the culprit antigens are still controversial. The study was undertaken to examine 100 patients with chronic RHD and 100 controls for HLA class I and class II antigens for differences in prevalence. All samples were typed at the HLA-DRB1/3/4/5 and DQB1 loci by the sequence-specific primer (PCR-SSP) method at low resolution. For HLA class I antigens, HLA-B13 frequency was marginally increased in patients with RHD compared to controls without reaching statistical significance. For class II antigens, RHD patients had higher frequencies for HLA-DRB1*01 (RHD 24%, controls 10%), DRB1*04 (RHD 35%, controls 26%), DRB1*07 (RHD 18%, controls 11%) and HLA-DQB1*02 (RHD 32%, controls 17%) without reaching statistical significance, and significantly lower frequencies for DRB1*13 (Pc < 0.003, OR: 5.69), DRB5* (Pc < 0.003, OR: 33) and DRB3* (Pc = 0.03, OR: 2.66) compared to controls. It was concluded that host, microbial and environmental factors collude to create acute rheumatic fever (RF) and chronic rheumatic valve disease. The HLA-DRB1*13, DRB5* and DRB3* were protective against the development of rheumatic valve damage.

The role of HLA antigens in chronic hepatitis B virus infection

OBJECTIVE

To investigate the mechanism underlying the development of chronic hepatitis B virus infection (HBV) in Turkish population using HLA tissue typing.

METHODS

The study group I consisted of 20 patients with HBV-related chronic liver disease (cirrhosis, chronic active hepatitis or chronic persistent hepatitis). The study group II included 30 HBV chronic carriers. The control group consisted of 50 healthy subjects with negative serologic markers for HBV. HLA typing was performed by Terasaki's microlymphocytotoxicity method.

RESULTS

The frequencies of HLA-DR13 and DQ3 were significantly higher in the patients with HBV-related chronic liver disease compared to those of control group. The absence of HLA-A24 and CW1 was also significant in group I. The frequencies of HLA A2, B8, B13, CW3, DR13 were significantly higher in group II compared to the control group. There were increased frequencies of HLA- B8, B13, DR7, DR13, and DQ3 in both group I and group II.

CONCLUSION

HLA-A24 AND Cw1 were associated with low risk for HBV-related chronic liver disease and HLA- B13, B8, DR7, DR13 and DQ3 were associated with high risk for chronic HBV infection in the Turkish population (JPMA 52:253;2002).

Genes of major histocompatibility complex class II influence chronic C hepatitis treatment with interferon in hemodialysis patients

The prevalence of anti-HCV among patients on hemodialysis is consistently higher than in the general population, indicating that patients on hemodialysis programs are at risk of acquiring HCV infection. The response to interferon alpha 2b (IFN -alpha 2b) therapy in chronic C hepatitis depends on viral and host factors. We treated 22 chronic C hepatitis uremic patients with IFN -alpha 2b (3 MU three times a week) and compared interferon responsive and unresponsive patients with regard to HLA II genes. HLA II genes were investigated by PCR-SSP low resolution, anti-HCV with ELISA II and HCV-RNA with reverse transcriptase "nested" PCR.

FINDINGS

HLA DRB1*13 is 50% positive in the non-responder group (four women, four men, mean age; 28.8+/-11.9 years) and 7% in the responder group (five women, nine men, mean age; 32.2+/-7.8 years) (p<0.05). There was no difference with respect to HLA genes between controls (six women, eight men, mean age; 29.5+/-12.8 years) and patients (nine women, 13 men, mean age; 31.0+/-9.3 years) (HLA DRB1*13 is 28% and 22% positive, respectively). We conclude that major histocompatibility complex class II genes influence the outcome of chronic C hepatitis treatment with IFN -alpha 2b.

Relationship between gingival hyperplasia and class II histocompatibility antigens in renal transplant recipients

Gingival hyperplasia, a well-known side effect of ciclosporin A (CS-A), is much more prominent when CS-A is used in combination with calcium channel blockers, especially dihydropyridines. On the other hand, it is interesting to note that this complication is not observed in all patients using this drug combination. This study was conducted in order to investigate the relationship (if any) between major histocompatibility complex antigens and gingival hyperplasia. Seventy-six renal transplantation patients were evaluated by an experienced dentist for gingival hyperplasia. The patients were then divided into two groups according to the presence (group 1, n = 18) or absence (group 2, n = 58) of gingival hyperplasia. There was no significant difference between the two groups regarding age, sex, transplant age, donor type, antihypertensive and immunosuppressive therapy protocols, and CS-A levels. HLA-DR2 antigen was present in 63% of the patients with gingival hyperplasia and in 34% of the patients without gingival hyperplasia. However, the HLA-DR1 antigen frequencies were found to be 11 and 22% in group 1 and group 2, respectively. In patients receiving nifedipine as an antihypertensive therapy, gingival hyperplasia developed more often than in patients receiving verapamil or diltiazem. As a result, in renal allograft recipients with HLA-DR1 antigen, gingival hyperplasia was seen less frequently than in HLA-DR2-positive patients. It is believed that the presence of these antigens regulates the response of the patients to either CS-A and/or calcium channel blockers.

The osmotic migration of cells in a solute gradient

The effect of a nonuniform solute concentration on the osmotic transport of water through the boundaries of a simple model cell is investigated. A system of two ordinary differential equations is derived for the motion of a single cell in the limit of a fast solute diffusion, and an analytic solution is obtained for one special case. A two-dimensional finite element model has been developed to simulate the more general case (finite diffusion rates, solute gradient induced by a solidification front). It is shown that the cell moves to regions of lower solute concentration due to the uneven flux of water through the cell boundaries. This mechanism has apparently not been discussed previously. The magnitude of this effect is small for red blood cells, the case in which all of the relevant parameters are known. We show, however, that it increases with cell size and membrane permeability, so this effect could be important for larger cells. The finite element model presented should also have other applications in the study of the response of cells to an osmotic stress and for the interaction of cells and solidification fronts. Such investigations are of major relevance for the optimization of cryopreservation processes.

Clinical effects of periodontal therapy on the severity of cyclosporin A-induced gingival hyperplasia

BACKGROUND

Gingival hyperplasia (GH) is a major side effect associated with cyclosporin A (CsA) therapy. The condition is further augmented due to the gingival inflammation. In this study, the effects of initial periodontal therapy and gingival curettage are analyzed in a group of patients with clinically significant (>30%) CsA-induced gingival hyperplasia.

METHODS

The test group of 15 patients received oral hygiene instructions, supra- and subgingival scaling, polishing, and gingival curettage only oral hygiene instructions were given to 16 control subjects. Plaque index (PI), gingival index (GI), calculus index (CI), periodontal probing depth (PD), and gingival hyperplasia were recorded at baseline and repeated 8 weeks after treatment. Current doses of immunosuppressive agents, serum concentrations of CsA, and duration of CsA therapy were recorded as the pharmacological parameters.

RESULTS

Statistical evaluation revealed that all clinical variables showed statistical decreases compared to baseline in the treated patients, while none of the parameters changed significantly in the control group. Initial GH scores of 53.63% in controls and 53.40% in the treated patients were 52.83% and 32.13% following treatment, respectively. A difference of 21.27% in the severity of treated GH was accompanied by a 0.56 decrease in GI scores in the test group.

CONCLUSIONS

Compared to the initial observations, the results suggested that nearly 60% of the condition could be of fibrotic origin. Initial periodontal therapy and curettage resulted in the resolution of the inflammation in CsA-induced GH. Further investigation of the treated patients has shown that 7 out of 15 patients (47%) in the test group responded well and their GH scores decreased below 30% at the end of the study. The treatment in this study was effective in eliminating the necessity of more extensive surgical modes of treatment, such as gingivectomy, in 47% of cases.

Analysis of peripheral blood leukocytes in patients with cyclosporine A-induced gingival hyperplasia

BACKGROUND

Gingival overgrowth is one of the major adverse effects of the immunosuppressive drug cyclosporine A (CsA). Although several studies have attempted to determine the immunological mechanisms of gingival hyperplasia (GO) due to CsA therapy, the pathogenesis remains unclear. In this study, the distribution of the peripheral blood leukocytes in a group of renal transplant patients undergoing CsA therapy was analyzed and possible correlations of periodontal and pharmacological variables to lymphocyte subpopulations, natural killer cells, and monocytes investigated.

METHODS

Thirty-six patients were classified into 2 groups of 18 each according to the degree of gingival overgrowth. The periodontal evaluation included plaque index (PI), gingival index (GI), gingival overgrowth (GO), calculus index (CI), and probing depth (PD). The pharmacological variables of current doses of the therapeutic serum levels of CsA were investigated. The peripheral blood leukocytes were studied by 2-color flow cytometric analysis using anti-human CD2, CD3, CD4, CD8, CD11b, CD11c, CD16, CD19, HLA-DR, and CD3+HLA-DR+ monoclonal antibodies.

RESULTS

Statistical evaluation revealed that none of the pharmacological variables varied between the 2 groups. Responders (GO >30%) had significantly higher GI, PD, and GO scores compared to nonresponders (GO < or =30%). Of the immunological parameters studied, only CD2 was higher in the responder group. None of the clinical parameters correlated to the immunological values.

CONCLUSIONS

The results of this study may be useful in explaining the underlying mechanisms of drug-induced gingival overgrowth. Several previously unsuspected cells and accessory activation mechanisms for T lymphocytes could play a role in the pathogenesis.

[Cryobiology of complex tissues]

Cooling biomaterials to liquid-nitrogen temperature is probably the most effective procedure for the preservation of their biochemical and morphological parameters, in so far as adverse effects of cooling are controlled. Potential damage has not the same explanation under different conditions of cold exposure. Even a moderate decrease of temperature leads to irreversible damage when applied to untreated organisms. Deep freezing injuries are due to crystallization of ice, and cellular consequences are quite different according to the temperature kinetics. The fraction survival, as a function of hypothermic kinetics, has a bimodal distribution, reflecting two distinct mechanisms: a first process, concomitant of a slow cooling rate, with extracellular ice formation, and a second one, during fast cooling rates, with intracellular ice formation. Thereby, cryopreservation protocols have to focus on many variable factors, including choices of a cryoprotectant, which delays ice formation, and a cooling rate leading to an optimal cell survival. Under these conditions, osmotic effects are almost neutralized. Nevertheless, these methods can be applied only to isolated cells. For tissues or organs, ice formation should be avoided at low temperatures. Vitrification is the corresponding process by which tissue water is undercooled to the glass transition temperature and solidified into the amorphous or glassy state. Very high cooling and warming rates are needed. The use of an appropriate cryoprotective agent mixture, called a "vitrification solution" should be useful: however, high-concentration vitrification solutions have still undesired toxic effects. Finally, an optimal cryoprotectant, in terms of cooling/warming rates and toxicity, has to be found.

CNS axonal regeneration with peripheral nerve grafts cryopreserved by vitrification: cytological and functional aspects

To test cool-warm protocols for storing peripheral nerves, 4-cm-long-nerve segments were removed from the hindleg of adult rats and cryopreserved using a vitrification solution (or cryoprotective mixture) containing a mixture of polyalcohols (2,3-butanediol, 1,2-propanediol, polyethylene glycol, and Belzer U.W. medium). Schwann cell viability and morphology were studied with regard to the effect of (i) cryoprotective mixture concentration (100, 50, and 30% diluted in human serum albumin at 4%), (ii) duration of exposure (10, 15, or 30 min in a single step) of nerves to the cryoprotective mixture, (iii) cooling rate (F1/F2, F3, and F4: 3, 12, and 231 degrees C/min, respectively), and (iv) type of replacement of cryoprotectant (T1, one step; or T2, perfusion) after warming. Nerves exposed 10 min to cryoprotective mixture 50% (2,3-butanediol, 1.926 mol.liter-1; 1,2-propanediol, 3.063 mol.liter-1; polyethylene glycol, 0.084 mol.liter-1; and Belzer U.W., 22.4 mosm-1) and cooled-warmed with the F2/F3/F4-T2 protocols contained live and correctly cryopreserved Schwann cells. The capacity of these cryopreserved nerve segments (n = 6) to be subsequently repopulated by regenerating axons from central neurons was compared to that of fresh nerves when used as peripheral nerve autografts implanted within the spinal cord at the level of the descending respiratory pathways. All cryopreserved nerve grafts were successfully reinnervated by regenerated central axons. Unitary spontaneous action potentials propagated along these axons were assessed by recording the discharge of tested nervous filaments (T) from the grafts in artificially ventilated and paralyzed animals. Out of 535 T, 32 (6 +/- 1.2%) presented spontaneous unitary activity with respiratory (R, n = 2) and nonrespiratory (NR, n = 30) pattern of discharge. The T mean number, the occurrence rate referenced to the total number of T (R/T, NR/T, and R + NR/T) and the mean number of spontaneous units (R, NR, R + NR) were compared to those of fresh spinal peripheral nerve grafts. Except for T, cryopreserved peripheral nerve grafts contained statistically significantly (P < 0.05) less spontaneous R and NR unitary activity, which represented, respectively, 6.2 +/- 6.2 and 26.8 +/- 5.7% of that found in the control group. These data indicate that nerves cryopreserved with the protocols described above contain viable Schwann cells which constitute a suitable support to induce regeneration of central fibers. The effectiveness of nerve cryopreservation by vitrification is discussed with regard to Schwann cell viability following cool-warm protocols and to subsequent reinnervation of the cryopreserved peripheral nerve grafts.

The effect of verapamil on the prevalence and severity of cyclosporine-induced gingival overgrowth in renal allograft recipients

Cyclosporine A (CsA) and verapamil are two agents used in renal transplantation, both of which are suspected of inducing gingival overgrowth. This study was conducted to investigate the effect of verapamil on the severity and prevalence of CsA-induced gingival overgrowth. Fifty-one (51) renal transplant recipients (total group) of whom 22 were using only CsA (Group A) and 29 of whom were prescribed CsA + verapamil (Group B) were evaluated for various periodontal and pharmacological parameters. No statistically significant differences were found in age, sex, plaque index, gingival index, calculus index, probing depth, CsA oral dose, CsA whole blood level, duration of CsA therapy, azathioprine dose, and prednisolone dose. Although the prevalence of the gingival overgrowth was more pronounced in CsA + verapamil group compared to CsA group (51.72% vs. 40.91%), the difference was not statistically significant. Similarly, the severity of gingival overgrowth, although more manifest in CsA + verapamil group than CsA patients (34.24% vs. 28.91%), was not significantly different. Gingival overgrowth scores in the main group, CsA, and CsA + verapamil groups were found to be positively correlated to periodontal probing depths (r = 0.60, r = 0.70, r = 0.52, respectively) and the gingival index (r = 0.60, r = 0.70, r = 0.54, respectively). CsA oral dose, whole blood level, and duration of CsA therapy were not found to be correlated with the gingival overgrowth in either group. Likewise, the dose of verapamil and the duration of verapamil therapy were not correlated with the gingival overgrowth in Group B. This study indicates that verapamil, when prescribed as the calcium channel blocker in renal transplant patients, has no augmenting effect on the severity and the prevalence of CsA-induced gingival overgrowth.

Evaluation of the frequency of HLA determinants in patients with gingival overgrowth induced by cyclosporine-A

This study has been designed to investigate the immunogenetic susceptibility of Cyclosporine-A (CsA) immunosuppressed renal transplant patients to development of gingival overgrowth, and the amplifying effect of calcium channel blockers on the severity of this clinical entity. 52 renal transplant recipients were selected and initially grouped as follows: group (Gp)1: CsA (n = 7); Gp 2: CsA + verapamil (n = 26); Gp 3: CsA + diltiazem (n = 6); Gp 4: CsA + nifedipine (n = 13). These groups were not found to be significantly different in age, sex, plaque index (PlI), gingival index (GI), calculus index, periodontal probing depth, serum CsA level, or duration of CsA therapy (p > 0.05). No significant (p > 0.05) additive effect of the calcium channel blockers on the gingival overgrowth (GO) was assessed. The main group (n = 52) was evaluated for the correlations between the clinical and the pharmacological variables and the GO. GI (rs = 0.60) and the periodontal probing depth (rs = 0.71) were found to be moderately correlated with the GO. The patients were regrouped based on the severity of overgrowth and recognized as responders (n = 26) and nonresponders (n = 26). Age, sex, calculus index, serum CsA level, duration of the CsA therapy, were not statistically different among these groups (p > 0.05). PlI, GI, periodontal probing depth, and GO were significantly higher in the responder group (p > 0.05). Analysis of HLA distribution of the responders and the nonresponders and comparison with the controls (n = 3731) revealed that a statistically significant (p < 0.001)% of the nonresponders were positive for HLA-DR1. These data would indicate that an immunogenetic predisposition should be suspected in the pathogenesis of the entity, and that HLA-DR1 would have a protective rôle against gingival overgrowth induced by CsA.

Association between HLA antigens and early onset periodontitis

HLA-A, B, C and DR antigen frequencies were determined in a group of patients with juvenile periodontitis and rapidly progressive periodontitis. In juvenile periodontitis patients, HLA-A24 and DR4 were found at a significantly higher level than in the control group, and in rapidly progressive periodontitis patients, A9 and DR4 were found at a significantly higher level than the control group. The presence of these antigens gives evidence as to the susceptibility of various forms of early onset periodontitis.

Human lymphocyte antigens (HLA) and Graves' disease in Turkey

To evaluate the association of HLA types with Turkish patients with Graves' disease, HLA typing, clinical findings, and thyroid antibodies were correlated. The HLA types, clinical findings (ophthalmopathy and age at onset), and thyroid stimulating hormone (TSH) receptor (TRAb) and antithyroid microsomal antibodies (MAb) were analyzed. Seventy Turkish patients with Graves' disease and 306 control subjects were assessed. Serological HLA typing was performed in HLA A, B, C, DR, and DQ loci. There was a significantly increased prevalence of HLA B8, B49, DR3, DR4, and DR10 in Graves' disease. The association of Graves' disease with HLA DR3 was found to be less strong than previously described. The HLA DR4 antigen may contribute to the predisposition of Graves' disease in Turkey. The results suggest that HLA B7, B13, DR7, DQw2, and DQw3 may confer a protective effect for Graves' disease in Turkey. Patients carrying HLA B12, B18, and B44 haplotypes had a tendency to develop the disease at a later age. The difference from the other studies may be the result of the selection of the controls; in part, of the variability in serological typing reagents; and, also, of the rather weak HLA associations with the disease.

HLA antigens in Turkish race with rheumatic heart disease [see comment]

BACKGROUND

Rheumatic valvular disease has been reported to be associated with HLA antigens. To determine whether genetic factors could be involved in the pathogenesis of rheumatic heart disease (RHD), we analyzed the distribution of HLA-A, HLA-B, and HLA-DR antigens in Turkish patients with chronic rheumatic heart disease.

METHODS AND RESULTS

The association of class I and class II HLA antigens was examined in 107 ethnic Turkish patients with chronic RHD. The diagnosis was supported by echocardiography, cardiac catheterization, angioventriculography, and histological findings in patients who underwent valve replacement. Two hundred three control subjects, also of Turkish origin, were chosen. The phenotypes B16, DR3, and DR7 were encountered in a significantly higher frequency in patients with RHD compared with the control population (corrected p < 0.05, p < 0.00005, and p < 0.0005, respectively). There also was a decrease in the antigen frequency of DR5 in patients compared with controls (corrected p < 0.005).

CONCLUSIONS

The results are consistent with the hypothesis that susceptibility to RHD is genetically linked, and this in turn may be associated mainly with HLA class II antigens and weakly with class I antigens, with DR3, DR7, and B16 influencing susceptibility and DR5 conferring protection.

Isolation of protein uH2A using a one step preparative gel electrophoresis

A one step electrophoretic procedure for the isolation of protein uH2A has been devised which may improve the overall yield. The improvement involves elimination of intermediate steps which might result in the decrease of the yield. The method may serve as an alternate to the conventional methods and can also be used successfully for the isolation of several different proteins.

Studies on transcription termination and splicing of the rRNA precursor in vivo in the presence of proflavine

In isolated nucleoli from Tetrahymena thermophila, low concentrations of the intercalating agent proflavine inhibit both transcription termination and splicing of the rRNA precursor. Proflavine also exerts an in vivo effect on the process of transcription termination under conditions, where the growth rate is only slightly reduced. Thus, approximately 40% of the rRNA precursor molecules, accumulated in nucleoli during 60 min of treatment with the drug, are longer than the normal 35S rRNA precursor. R-Loop mapping of these longer precursor molecules isolated after 30 and 60 min of incubation demonstrates that the RNA polymerases have a 50 fold lower elongation rate in the spacer region than in the coding region. Proflavine in the given concentration is found to have no significant effect on the splicing of properly terminated precursor molecules. In contrast, none of the longer non-terminated molecules are found to be spliced. These results indicate that proflavine primarily affects the process of transcription termination and that the splicing event is inhibited due to the improper termination of the precursor molecule.

In vitro splicing of the ribosomal RNA precursor in isolated nucleoli from Tetrahymena

The macronuclear rRNA genes of Tetrahymena thermophila contain an 0.4 kb intervening sequence in the 26S rRNA coding region. The sequence is represented within the primary transcription product. We demonstrate in this paper that the enzyme activities necessary for the endonucleolytic cleavage as well as for the ligation of the transcript are associated with the isolated. The intervening sequence is excised as an unique molecule, which is stable in vitro. About 50% of the in vitro synthesized RNA is processed. Faithful in vitro transcription occurs in the presence of the divalent ions Mg2+, Mn2+ and Co2+ while processing takes place only in the presence of Mg2+. The absolute requirement for Mg2+ in the excision reaction enables us to synthesize labelled pre-rRNA in the presence of Mn2+ or Co2+. The synthesized RNA can be used as a substrate in studies of th processing enzymes in vitro.