Multicenter Evaluation of the Clinical Performance and the Neutralizing Antibody Activity Prediction Properties of 10 High-Throughput Serological Assays Used in Clinical Laboratories.

As the coronavirus disease 2019 (COVID-19) pandemic second wave is emerging, it is of the upmost importance to screen the population immunity in order to keep track of infected individuals. Consequently, immunoassays for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with high specificity and positive predictive values are needed to obtain an accurate epidemiological picture. As more data accumulate about the immune responses and the kinetics of neutralizing-antibody (nAb) production in SARS-CoV-2-infected individuals, new applications are forecast for serological assays such as nAb activity prediction in convalescent-phase plasma from recovered patients. This multicenter study, involving six hospital centers, determined the baseline clinical performances, reproducibility, and nAb level correlations of 10 commercially available immunoassays. In addition, three lateral-flow chromatography assays were evaluated, as these devices can be used in logistically challenged areas. All assays were evaluated using the same patient panels in duplicate, thus enabling accurate comparison of the tests. Seven immunoassays examined in this study were shown to have excellent specificity (98 to 100%) and good to excellent positive predictive values (82 to 100%) when used in a low (5%)-seroprevalence setting. We observed sensitivities as low as 74% and as high as 95% at ≥15 days after symptom onset. The determination of optimized cutoff values through receiver operating characteristic (ROC) curve analyses had a significant impact on the diagnostic resolution of several enzyme immunoassays by increasing the sensitivity significantly without a large trade-off in specificity. We found that spike-based immunoassays seem to be better correlates of nAb activity. Finally, the results reported here will add to the general knowledge of the interlaboratory reproducibility of clinical performance parameters of immunoassays and provide new evidence about nAb activity prediction.

Influences of age, ethnic group, and skin sites on a provisory skin marking, experimentally induced, in vivo.

BACKGROUND: To study capacity of skin to being imprinted by a marking head rapidly applied (10 seconds) onto the skin under a standardized pressure (15 kPa). MATERIAL AND METHODS: Referential photographs of skin markings, resulting from different times of application serve at grading the extent of skin imprints. The imprinting tool, equipped with 5 linear bulbs of different sizes but same thickness (1 mm), was applied onto the cheeks of 641 women of different ages (18-80 years) of 3 different ethnic groups. In the cohort of 198 Caucasian women, the marking head was pressed onto 3 different sites (outer arm, cheek, and dorsal forearm) and the kinetics of skin recovery from cheek marking was recorded on a smaller and younger part of this Caucasian cohort, ie, 141 Caucasian women, aged 18-59 years. RESULTS: The recorded intensities of skin markings were found highly correlated with age in all 3 studied ethnic groups (Chinese, African-American, and Caucasian). Caucasian women seem more sensitive to the marking and the kinetics of recovery from such imprint was found highly dependent from its intensity, ie, the higher the grades, the slower the recovery. In Caucasian women, intensities were different between skin sites, where arm showed higher resistance to marking. Possible impact of photo-aging on the decreased skin resistance to such provoked deformation is likely of minor amplitude, as compared to the one induced by chronological aging. CONCLUSION: This method offers a new vision on skin aging, in its variable response to a standard deformation that appears mostly driven by chronological aging.

Evaluating age-related changes of some facial signs among men of four different ethnic groups.

BACKGROUND: The alterations of some facial characteristics, with age, in men of different ethnic groups are a scarcely studied topic. OBJECTIVE: To illustrate and grade, among men of four different ethnic descents (Asians, African-Americans, Caucasians, Indians), aged 18-80 year, the changes in the severity of some facial signs occurring with age. METHODS: Digital Photographs (full face, profile, 45°) of 1058 subjects were taken under standard conditions of lightning. These allowed us to zoom in on 15-20 different facial signs on all subjects. Their observations by 15 trained experts, under calibrated screens, allowed these signs to be graded, with the help of four referential skin Atlases, specific to the gender and ethnic groups studied. RESULTS: Most facial signs show a rather regular increase with age, with different kinetics according to the ethnic group. The major changes, in all four ethnic groups, mostly concern skin structural alterations (wrinkles, neck sagging or texture). The changes in the severity of some wrinkles (forehead, inter-ocular…) may be viewed as ethnic signatures. The modifications in pigmentation disorders seem more closely linked to the constitutive skin pigmentation (photo-types), among which pigmentary spots are confirmed as a more specific Asian trait. CONCLUSION: Men of four different ethnic origins present different and ethnic-related facial alterations with increasing age, of different amplitudes.

A new tool to quantify the geometrical characteristics of facial skin pores. Changes with age and a making-up procedure in Caucasian women.

BACKGROUND: Facial skin pores (FSP) are common and benign signs that generate frequent esthetic concerns or complaints. Despite their worldwide prevalence, related literature remains scarce. Hence, a new device has been developed and applied to validating studies, aiming at best describing FSP as they are self-perceived, i.e. their anatomic features, their possible alterations with age and their appearance after application of a make-up product. METHODS: Dermascore+® is an imaging device dedicated to a direct observation and acquisition of various characteristics of the skin surface. Images are captured under a high magnification and under different lighting configurations, to highlight the skin relief, based upon parallel polarized images. Dedicated software allows FSP to being detected and their morphological parameters to being extracted and computed. By measuring each detected FSP in a given region of interest, a statistically significant impact of both age and an applied cosmetic product upon their morphological features can be observed and quantified. RESULTS: Although the size and density of FSP are not affected by aging, their shape becomes elongated. A few tested make up products show variable effects that closely correlate with visual assessments made by trained estheticians. CONCLUSION: The shape of FSP present on cheeks shows age-related changes, toward a more elongated aspect, likely linked to a progressively altered (more isotropic) skin surface micro-relief. The new tool Dermascore+® allows foundations to being rapidly differentiated and screened according to their variable effects upon the visual appearance through instrumental, objective depiction of FSP.

Influence of gravity upon some facial signs.

OBJECTIVES: Facial clinical signs and their integration are the basis of perception than others could have from ourselves, noticeably the age they imagine we are. Facial modifications in motion and their objective measurements before and after application of skin regimen are essential to go further in evaluation capacities to describe efficacy in facial dynamics. Quantification of facial modifications vis à vis gravity will allow us to answer about 'control' of facial shape in daily activities. METHODS: Standardized photographs of the faces of 30 Caucasian female subjects of various ages (24-73 year) were successively taken at upright and supine positions within a short time interval. All these pictures were therefore reframed - any bias due to facial features was avoided when evaluating one single sign - for clinical quotation by trained experts of several facial signs regarding published standardized photographic scales. RESULTS: For all subjects, the supine position increased facial width but not height, giving a more fuller appearance to the face. More importantly, the supine position changed the severity of facial ageing features (e.g. wrinkles) compared to an upright position and whether these features were attenuated or exacerbated depended on their facial location. Supine station mostly modifies signs of the lower half of the face whereas those of the upper half appear unchanged or slightly accentuated. These changes appear much more marked in the older groups, where some deep labial folds almost vanish. These alterations decreased the perceived ages of the subjects by an average of 3.8 years. CONCLUSION: Although preliminary, this study suggests that a 90° rotation of the facial skin vis à vis gravity induces rapid rearrangements among which changes in tensional forces within and across the face, motility of interstitial free water among underlying skin tissue and/or alterations of facial Langer lines, likely play a significant role.

Instrumental and clinical studies of the facial skin tone and pigmentation of Shanghaiese women. Changes induced by age and a cosmetic whitening product.

The pigmentation patterns of facial skin of 354 healthy Chinese women aged 18-80 years were investigated clinically and instrumentally. Chromasphere(®) was used to acquire pictures from the cheeks of subjects. Facial skin tone was described by L* parameter from the L,a,b system as well as Individual Typology Angle (ITA). Results show that skin tone becomes significantly darker along the life span. Both size of hyper-pigmented spots and their contrast with surrounding skin were found increased with age. As additional study, 40 women from these 354 subjects were asked to apply daily a whitening cosmetic product for a 2-month period. Such application led to a significantly lighter skin tone, although this study was not vehicle controlled and we cannot exclude that the increase in L* observed was in some part because of cumulative effects of previously used whitening products, there was an association with lighter skin tone as assessed through both instrumental measurements and self-perception by most subjects.

Effect of fertilizer formulation and bioaugmentation on biodegradation and leaching of crude oils and refined products in soils.

The effects of soil characteristics and oil types as well as the efficacy of two fertilizer formulations and three bioaugmentation packages in improving the bioremediation of oil-contaminated soils were assessed as a means of ex situ treatment selection and optimization through seven laboratory microcosm studies. The influence of bioremediation on leaching of oil from the soil was also investigated. The studies demonstrated the benefits ofbiostimulation to overcome nutrient limitation, as most of the soils were nutrient depleted. The application of both liquid and pelleted slow-release N and P fertilizers increased both the hydrocarbon biodegradation rates (by a factor of 1.4 to 2.9) and the percentage of hydrocarbon mass degraded (by > 30% after 12 weeks and 80% after 37 weeks), when compared with the unamended soils. Slow-release fertilizers can be particularly useful when multiple liquid applications are not practical or cost-effective. Bioaugmentation products containing inoculum plus fertilizer also increased biodegradation by 20% to 37% compared with unamended biotic controls; however, there was no clear evidence of additional benefits due to the inocula, compared with fertilizer alone. Therefore biostimulation is seen as the most cost-effective bioremediation strategy for contaminated soils with the levels of crude oil and refined products used in this study. However, site-specific considerations remain essential for establishing the treatability of oil-contaminated soils.

Neutralization of mitogenic lectins by intravenous immunoglobulin (IVIg) prevents T cell activation: does IVIg really have a direct effect on T cells?

Intravenous immunoglobulin (IVIg) is used for the treatment of an increasing number of autoimmune diseases. Clinical observations on IVIg-treated patients have revealed a modulation of T cell populations and functions in these patients. In vitro studies aimed at understanding the mechanisms underlying the effects of IVIg on T cells led to the conclusion that IVIg directly affected lectin-activated T cell functions. However, more recent studies have suggested the absence of a direct effect of IVIg on T cells. In the present work, we revisited the effect of IVIg on T cells using lectin-stimulated human T cells and showed that IVIg inhibited T cell functions only when added simultaneously with the activating lectin. Further, we showed that IVIg depleted from lectin-reactive IgG was no longer inhibitory, suggesting that the effect of IVIg on T cells was the consequence of lectin neutralization, possibly by interaction with glycans present in F(ab')(2) portion of IgG molecules. Our results challenge the previously widely accepted notion that IVIg exerts its anti-inflammatory effects by acting directly on T cells and suggest that effects of IVIg observed in treated patients are rather a consequence of the recently reported inhibitory effect of IVIg on antigen presentation.

Immunomodulatory effects of therapeutic preparations of human albumin.

BACKGROUND AND OBJECTIVES: Albumin is the most abundant protein in plasma and is considered to be immunologically inert. However, we recently observed that therapeutic human albumin preparations, used as protein control in studies involving high doses of IVIg, modulated the MHC II-restricted activation of antigen-specific T cells. In the present work, we characterized this effect in more details. MATERIALS AND METHODS: An in vitro antigen presentation assay using mouse cells was used to evaluate the effect of therapeutic human albumin preparations on the activation of ovalbumin-specific T cells. Flow cytometry and quantitative real-time PCR were used to monitor the expression of genes involved in this process. RESULTS: Therapeutic human albumin preparations increased T cell activation in a dose-dependent manner. The effect was explained by an increase in the expression of MHC II and of two other genes (CIITA and H2-M) involved in antigen presentation by murine monocytic cells. Similarly, the expression of HLA-DR on the surface of human monocytic cells was increased following incubation with therapeutic human albumin preparations. CONCLUSION: Altogether, these results reveal a possible physiological role of albumin in immunological processes, leading to an increased ability of antigen presenting cells to trigger T cell activation. This immunomodulatory effect needs to be considered, at least in studies in which albumin is used as a presumably inert control protein.

Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages.

The facial skin of 354 women, aged 18-80, living in Shanghai, was investigated over two successive 6-month periods, summer and winter. Results from clinical assessments indicate that aging signs, such as wrinkling and sagging, are unaffected over such period. However, physical measurements revealed alterations in some functional criteria of the skin, such as sebum output, skin colour, melanin content of pigmented spots, skin hydration, all being increased during summer. The relationships between all criteria, as well as technical or applied inferences/consequences from this study, are discussed.

Clinical study on the effects of a cosmetic product on dermal extracellular matrix components using a high-resolution multiphoton tomograph.

BACKGROUND/PURPOSE: The aim of this study was to demonstrate the effects of selected plant extracts in a cosmetic cream on the dermal network components after a 3-month treatment using an in vivo multiphoton tomographic device. METHODS: Twenty-four Caucasian women aged between 45 and 65 applied randomly a cosmetic emulsion B containing active ingredients (soy and jasmine) twice a day on one arm and its vehicle A (without active ingredients) on the other arm during 3 months. Measurements were performed on the internal side of the forearm before starting the treatment (T0), after 4 week (T4) and 12 weeks (T12) treatment. Measurements consisted of a multi-layers acquisitions using a multiphoton tomograph with subcellular resolution. Optical sections (about 6 microm thick) were recorded from 0 to about 200 microm using two different wavelengths: 760 and 820 nm. To compare the series of images and obtain an objective quantification of the signal of second harmonic generation (SHG) and autofluorescence, the method used consisted of taking the integrated brightness of an image (same rectangular area for all images) as a measure of the signal. Following this step, a ratio between brightness of images from the area treated with cream A or B and brightness of untreated area was calculated and used as an assessment of treatment efficacy. The parameter used for statistical analysis (variance analysis) is the difference before and after 12 weeks of treatment by either cream A or B of the signal ratios calculated in the upper dermis (118-130 microm) and those from a deeper region of the upper dermis (165-178 microm). RESULTS: Signals (autofluorescence+SHG) of extracellular matrix do not change significantly with time (weeks 0, 4 and 12) when cream A (vehicle with no active ingredient) is applied. Treatment with cream B results in an enhancement in the signal level of extracellular matrix at week 12. The comparison of signals, in both areas (118-130 microm and 160-178 microm), show an higher increase in the deeper region than in the more superficial one for product B while we do not notice any change with product A. CONCLUSION: The multiphoton tomograph provided excellent high-resolution images, which describe clearly the different skin layers, single cells and extracellular matrix components in all the 24 volunteers. Statistic analyses reveal a real effect for product B with selected plant extracts, known to increase collagen synthesis. Changes observed are characteristics of modifications in dermal collagen and elastin content. To our knowledge, it is the first time that it was possible to demonstrate in vivo the effect of a cosmetic product on the superficial dermal layer, in a non-invasive and non-destructive process, i.e. without cutting the skin.

Equivalence of face and volar forearm for the testing of moisturizing and firming effect of cosmetics in hydration and biomechanical studies.

The objective of the study was to compare measurements of skin hydration and of biomechanical properties performed on different zones of face and volar forearm. Two short-term (1 h) and two long-term (3 weeks) studies were conducted with a moisturizing and a firming product, respectively, on groups of female volunteers with dry skin. Measurements (Corneometer) and Dermal Torque Meter or DTM were performed on different zones of the face and of the volar forearm, 1 h after product application, and after 1, 2 and 3 weeks of repeated twice daily application. While the sebaceous-gland rich T-zone behaves differently, probably due to sebum/skin, sebum/product and/or sebum/measuring device interactions, there are no statistically significant differences between measurements made on temple, cheek, maxilla and volar forearm. The volar forearm is representative of the face for measuring skin hydration and biomechanical properties, and relevant for the assessment of the efficacy of cosmetic products destined for facial use.

Evidence for the presence of several phosphodiesterase isoforms in brown adipose tissue of Zucker rats: modulation of PDE2 by the fa gene expression.

The present study was undertaken to characterise the phosphodiesterases (PDEs) present in brown adipose tissue (BAT) of Zucker rat pups and to determine whether the capacity for degradation of cyclic nucleotides was affected by the fatty genotype. Regardless of the genotype, PDE2-4 contributed to total PDE activity, the PDE3 activity equalling the sum of PDE2 and 4 activities. In fa/fa compared to Fa/fa rats, (a) PDE2 activity was significantly increased, (b) Western blot analysis of PDE2 revealed two signals at 71 and 105 kDa, with changes in protein being in good parallelism with changes in activity, (c) the PDE2 mRNA concentration was also significantly increased. In good agreement, the cGMP concentration was decreased in BAT from fa/fa pups.

Effect of the elapsed time after the final antigen boost on the specificity of monoclonal antibodies produced by B cell hybridomas.

We have studied the effect of the number of days following the last antigen boost on the specificity of monoclonal antibodies produced by B cell hybridomas using spleen cells of mice immunized with human red cells of the A blood group. We showed, as previously observed by others, that the highest numbers of monoclonal anti-human red blood cells were obtained in fusions done 3 and 4 days after the final boost. However differential screening of the hybridoma cultures showed that the majority of the monoclonal antibodies reacting with the A blood group antigen were obtained in fusions done only 2 days after the last antigen injection. These results show that the delay between the final boost and the fusion experiment can influence not only the total number of antibody-secreting hybridomas but also the specificity of the antibodies produced.

Increased proportion of B cell hybridomas secreting monoclonal antibodies of desired specificity in cultures containing macrophage-derived hybridoma growth factor (IL-6).

The addition of macrophage feeder cells or conditioned medium has been shown to increase the yield of murine hybridomas obtained after the fusion of myeloma cells and activated B lymphocytes. It has been shown recently that the conditioned medium contains a growth factor (HGF) active on newly formed hybridomas and that the human HGF is similar to B cell stimulatory factor 2 which can induce the synthesis of antibodies in transformed B cells. We have compared in several fusion experiments the stimulatory effects of HGF both on the yield of hybridomas and on the number of antibody-secreting hybridomas. The results obtained clearly showed that while the stimulatory effect of HGF on the yield of growth-positive wells was variable and sometimes barely detectable, the proportion of growth-positive wells containing monoclonal antibodies was consistently much higher in the HGF-containing cultures. These results suggest that the majority of the antibody-secreting newly formed hybridomas are sensitive to HGF and indicate that HGF is a very useful culture supplement for the generation of a high number of antibody-producing hybridomas even if it may not increase significantly the yield of viable hybridomas.

Use of hu-IgG-SCID mice to evaluate the in vivo stability of human monoclonal IgG antibodies.

Human and in vitro modified mAbs such as humanized rodent mAbs and immunotoxins are now considered for a variety of applications in humans. The adequate in vivo stability of these Ig preparations is not easily predicted from in vitro studies and may be essential for many therapeutic applications. In this study, we report the development and characterization of an in vivo model for testing this parameter using SCID mice containing a physiological concentration of human IgG (hu-IgG-SCID). The model was tested with several IgG1 and IgG3 human mAbs reacting with the human Rh(D) red cell antigen. It is known that human IgG have a shorter half-life in SCID mice than in humans. However, our results showed that the half-life of IgG3 mAbs (1.5 +/- 0.5 days) was much shorter than the one of IgG1 mAbs (5.8 +/- 1.4 days), indicating that the relative stability of IgG1 and IgG3 human mAbs in hu-IgG-SCID mice is similar to the one previously reported in humans (21 days vs. 7 days respectively). The IgG catabolism rate in humans is known to be inversely proportional to serum IgG concentrations. Accordingly, the dilution of the mAbs in a large excess (200-fold) of human IgG was found to be an important parameter of the hu-IgG-SCID mouse model since much longer (3-4-fold) mAb half-lives were obtained in the presence of a lower dose or in the absence of co-injected human IgG. This study show the usefulness of this animal model for the evaluation of human antibody stability in an in vivo environment.

Pretransplant and posttransplant antibodies in human corneal transplantation.

The purpose of this study was to measure the association between antibody formation and endothelial corneal allograft reactions in 533 consecutive corneal graft recipients. The median follow-up time of these recipients was 732 days. Pretransplant panel-reactive antibodies were not found to be associated with endothelial corneal allograft reactions. Out of 533 recipients, 239 developed posttransplant antibodies during the course of this study. The formation of posttransplant antibodies was frequent in recipients with pretransplant antibodies and in HLA-A,-B-incompatible recipients. Posttransplant antibodies most often appeared within the first six months after transplantation whereas endothelial allograft reactions most often occurred later. Out of 65 recipients who developed PPRA and underwent an allograft reaction, 53 had a PPRA peak prior to, or at about the time of, the allograft reaction. Corneal allograft reaction events diagnosed during the second and third year after surgery were correlated with PPRA formation during the first year after grafting. The 36-month reaction-free survival rate of transplants was estimated at 72% in recipients with PPRA compared with 86% in recipients without PPRA (log rank P value = 0.002). Furthermore, posttransplant antibody formation altered the outcome of corneal allografts in both HLA-A and -B-compatible and -incompatible recipients. These findings suggest that posttransplant antibody development represents a high risk of endothelial corneal allograft reactions.

Interaction of amiodarone and triiodothyronine on the expression of beta-adrenoceptors in brown adipose tissue of rat.

1. This study was undertaken to evaluate in vivo the influence of amiodarone on the effects of triiodothyronine (T3) in brown adipose tissue (BAT) which are independent of thyroid hormone synthesis and of the conversion of thyroxine (T4) to T3. Thyroidectomized rats were given a replacement dose of T3 (0.5 mg kg(-1) p.o. daily for 3 days) with or without amiodarone (50 mg kg(-1) p.o. daily for 1 week). 2. As assessed by RT-PCR, treatment of thyroidectomized rats with T3 caused a 2 fold decrease in beta3-adrenoceptor (beta3-AR) mRNA levels and a 2 fold increase in beta1-AR mRNA levels. 3. Binding studies using [3H]-CGP 12177 as a ligand showed that treatment of thyoidectomized rats with T3 resulted in a 70% decrease in beta3-AR number and in an 80% increase in beta1-AR in BAT membranes. 4. T3-treatment abolished the increase in BAT adenylyl cyclase (AC) activity induced by CGP12177 in thyroidectomized rats. It also decreased the amount of Gi protein (ADP-ribosylation) by 30%. 5. At variance with the literature on the heart, amiodarone administration did not inhibit the positive effect of T3 on beta1-AR expression in BAT in thyroidectomized rats. However, it antagonized the effect of T3 on beta3-AR number, but not on AC activity or on Gi expression. 6. These results indicate that the effects of thyroid hormones on the responsiveness of BAT to catecholamines involves both receptor and post-receptor mechanisms, they also suggest that interaction between amiodarone and thyroid hormones is highly tissue-specific and depends on the beta-AR subtype.

Early modification of neuropeptide Y but not of neurotensin in the suprachiasmatic nucleus of the obese Zucker rat.

Hyperphagia in the obese Zucker rat is characterized by the early modification of the dark/light (D/L) rhythm of food intake. This rhythm is mainly driven by the suprachiasmatic nucleus (SCN) and, more controversially, by the ventromedian nucleus (VMN). In the SCN of adult obese Zucker rat, the concentrations of neuropeptide Y (NPY), a potent stimulator of food intake, are increased whereas those of neurotensin (NT), an anorexigenic peptide, are decreased. However, nothing is actually known about the synchronicity of the dysregulation of the D/L rhythm and variations of these peptides. That is why we measured NPY and NT in the microdissected SCN and VMN of lean (n = 16) and obese (n = 15) Zucker rats before the occurrence of hyperphagia (day 16 of age) and a few days after weaning (day 30 of age) when the modifications are apparent. For NPY, there was a very significant effect of age (P less than 0.001) for both nuclei and a significant effect of genotype (P less than 0.02) for the SCN only. NPY concentrations increased between 16 and 30 days in both nuclei (+74% (SCN) and +70% (VMN) in the obese rat; +57% (SCN) and +67% (VMN) in the lean rat; P less than 0.001). NPY in the SCN was not different at 16 days of age between lean and obese rats but significantly increased at 30 days in the obese rat (22.6 +/- 1.2 vs. 18.6 +/- 1.5 ng/mg protein; P less than 0.05). NT was not detected in the SCN of either group at 16 days or at 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of factors unrelated to tissue matching on corneal transplant endothelial rejection.

We examined 348 consecutive adult recipients of a corneal transplant for clinical signs of an endothelial rejection episode in a single-center follow-up study. The variables studied included primary diagnosis, number of previous corneal transplants, previous transplant failures from rejection episodes, transplant size, recipient corneal vascularization, donor age, recipient age and sex, past blood transfusions, and number of pregnancies. Five important risk factors were identified: primary diagnosis of herpetic, interstitial, or traumatic keratitis; transplant size 8 mm and larger; more than one previous corneal transplant; recipients younger than 60 years of age; and the presence of recipient corneal vascularization. This information will serve eventually for analyzing the effect of donor recipient tissue matching on corneal transplant rejection.