DUSP23 is over-expressed and linked to the expression of DNMTs in CD4+ T cells from systemic lupus erythematosus patients.

We evaluated the transcriptional expression of dual-specificity protein phosphatase 23 (DUSP23) in CD4+ T cells from 30 systemic lupus erythematosus (SLE) patients and 30 healthy controls. DUSP23 mRNA levels were considerably higher in the patient group: 1490 ± 1713 versus 294·1 ± 204·2. No association was found between DUSP23 mRNA expression and the presence of typical serological and clinical parameters associated with SLE. Meaningful statistical values were obtained in the patient group between the levels of DUSP23 and integrin subunit alpha L (ITGAL), perforin 1 (PRF1) and CD40L. Similarly, transcript levels of different DNA methylation-related enzymes [DNA methylation-related enzymes (DNMT1, DNMT3A, DNMT3B, MBD2, and MBD4)] were also correlated positively with the expression of DUSP23. In an attempt to counteract the hypomethylation status of the promoters of certain genes known to be over-expressed in SLE, it is possible that DUSP23 acts as a negative regulatory mechanism which ultimately silences the transcription of these epigenetically regulated genes by triggering an increase in the expression of different DNMTs.

Statin-associated autoimmune myopathy: A distinct new IFL pattern can increase the rate of HMGCR antibody detection by clinical laboratories.

BACKGROUND AND OBJECTIVE: Statin-associated autoimmune myopathy (SAAM) with anti-HMGCR antibodies has recently been described. Several specific immunoassays are in use to detect HMGCR antibodies. In the course of systematic autoantibody screening we recognized a new distinct IFL staining pattern on rat liver sections that regularly coincided with anti-HMGCR antibodies. In this study we investigated whether this new IFL pattern is specifically associated to statin-associated autoimmune myopathy and corresponds to anti-HMGCR antibodies. PATIENTS AND METHODS: Twenty-three patients positive for anti-HMGCR antibodies (14 diagnosed with SAAM) were investigated for anti-HMGCR antibodies by two ELISA assays and confirmed by immmunoblot. HMGCR associated liver IFL pattern (HALIP) was detected by indirect IFL and the reactivity against HMGCR was confirmed by immunoabsorption using purified human HMGCR antigen. 90 patients with other autoimmune diseases and 45 non-autoimmune statin treated patients were studied as controls. RESULTS: 21 out of 23 (91%) anti-HMGCR positive patients were HALIP positive. The staining was completely and specifically removed by immunoabsorption with human purified HMGCR. None of the control sera from autoimmune patients or non-autoimmune statin treated subjects was positive for HALIP. Statistical concordance between HALIP and anti-HMGCR antibody specific tests was 98.7%, kappa 0.95. CONCLUSIONS: A new and distinct IFL staining pattern (HALIP) is associated to HMGCR associated myopathy. Absorption and concordance studies indicate that the antigen recognized in the liver by HALIP is HMGCR or a closely related protein. Awareness of this new pattern can help to detect HMGCR autoantibodies in statin treated patients tested for autoimmune serology.

Sequence analysis of TMEM173 exon 5 in patients with systemic autoimmune diseases.

BACKGROUND: Overactivation of the interferon pathways has been demonstrated in patients suffering from different systemic autoimmune diseases (SADs). Genetic associations have been described for many genes involved in these pathways. Gain-of-function mutations in the TMEM173 gene have recently been reported in patients with autoinflammatory diseases that share some clinical features with SADs. METHODS: We aimed at detecting the reported three mutations of transmembrane protein 173 (TMEM173) exon 5 in 100 patients suffering from: systemic lupus erythematosus (SLE) (n = 22), primary antiphospholipid syndrome (PAPS) (n = 20), systemic sclerosis (SSc) (n = 20), dermatomyositis (DM) (n = 20), and vasculitis (n = 18). Samples from 19 healthy controls were also included. Sequence analyses were performed from the derived TMEM173 exon 5 PCR fragment amplified from DNA obtained from whole blood. RESULTS: Neither mutations nor single nucleotide polymorphisms (SNPs) in the exon 5 of the TMEM173 gene were detected. Just the rs7380272 SNP, located in the intronic region upstream exon 5, was detected in some patients and controls. The allele frequency of this SNP, though, was not statistically different between the patients groups and the control group. CONCLUSIONS: Our study demonstrates the lack of association between the presence of SADs and mutations in exon 5 of the TMEM173 gene. SADs are complex multifactorial diseases in which not just one but probably many different genetic alterations may coexist. Although we cannot rule out the possibility that other variations may exist in other regions of this gene, we think that studies must be directed towards the analysis of other genes which, as TMEM173, also code for nucleic acid sensors that activate the nucleic-acid induced type I IFN pathway.

Prevalence of HHV-8 in systemic autoimmune diseases.

BACKGROUND: Epidemiological data suggest that some viruses may be linked to the development of autoimmunity. OBJECTIVES: The objective of this work was to determine the presence of HHV-8 viral DNA in whole blood from patients suffering from different systemic autoimmune diseases (SAD). We also aimed at testing the prevalence of patients showing antibodies against an HHV-8 orfK8.1 peptide. STUDY DESIGN: Two hundred and eighty SAD patients and 50 healthy blood donor controls were included. Molecular analyses were performed by nested PCR from DNA obtained from whole blood and an enzyme immunoassay was developed in order to test for the presence of antibodies directed against a synthetic peptide derived from the HHV-8 orfK8.1 protein. RESULTS: Only 2 out of the 280 samples analyzed yielded the specific HHV-8 PCR product. Antibodies against orfK8.1 were detected in 2 SLE patients, 1 patient suffering from Sjögren's syndrome and 2 patients with vasculitis. CONCLUSIONS: We conclude that HHV-8 is usually not present in blood neither from autoimmune patients nor from healthy controls. Furthermore, HHV-8 antibodies against the HHV-8 orfK8.1 peptide were rarely detected. It leads us to infer that HHV-8 is not involved on the development of these disorders. It does not rule out the possibility that other environmental and microbiological triggers may account for their etiopathogenesis.

Beta2-glycoprotein I gene polymorphisms Val247Leu and Trp316Ser in Spanish patients with primary antiphospholipid syndrome.

The significance of beta2-glycoprotein I (ß2GPI) polymorphisms in the production of anti-ß2GPI and other antiphospholipid autoantibodies (aPL) and in the pathogenesis of primary antiphospholipid syndrome (PAPS) is not well understood. We performed a study comparing the distribution of polymorphisms at codons 247 (Val247Leu) and 316 (Trp316Ser) of the ß2GPI gene in a Caucasian Spanish population of PAPS patients and healthy controls, and then making correlations with the development of anti-ß2GPI antibodies and other aPL and associated clinical manifestations. A total of 57 PAPS patients and 100 control subjects were included. In the analysis of Val247Leu polymorphism, alleles (V and L) and genotypes (V/V, V/L, L/L) were similarly distributed in PAPS patients and controls (P = 0.66 and P = 0.22, respectively). Regarding Trp316Ser polymorphism, we found a higher percentage of patients with respect to controls expressing S allele (11.4 vs. 5%, P = 0.02) and T/S genotype (22.8 vs. 10%, P = 0.02). However, when we compared T/T and T/S genotypes in PAPS patients, we found no differences regarding generation of anti-ß2GPI, other aPL and clinical manifestations favoring any genotype. Our findings suggest that among Spanish Caucasians, polymorphisms at codon 247 (Val247Leu) do not seem to influence PAPS pathogenesis. On the contrary, polymorphisms at codon 316 (Trp316Ser), by means of an increased S allele and T/S genotype presence in Spanish Caucasian patients, might play a role in the pathogenic development of PAPS, although mechanism would not involve an increased production of anti-ß2GPI and other aPL.

The PTPN22*R620W polymorphism does not confer genetic susceptibility to antiphospholipid syndrome in the Spanish population.

In this work, we proposed to determine the association of the PTPN22*R620W SNP with primary antiphospholipid syndrome (PAPS) in a case-control association study of Spanish Caucasian individuals. A total of 81 PAPS patients were compared with 81 blood-donor healthy control subjects. PTPN22 SNP (R620W) genotyping was performed by using a polymerase chain reaction-restricted fragment length polymorphism assay. No statistically significant differences were found between control subjects and PAPS patients for the PTPN22*R620W genotypes (P = 0.214). No statistically significant differences were found according to either the presence or absence of antiphospholipid antibodies or the clinical manifestations associated to PAPS. Our results indicate that this functional PTPN22*R620W polymorphism is not associated to PAPS; it seems not to be a risk factor in our Spanish population. The effect of the PTPN22 SNP on clinical manifestations and presence of antiphospholipid antibodies in APS warrants further investigations.

Echocardiography at diagnosis of antiphospholipid syndrome provides prognostic information on valvular disease evolution and identifies two subtypes of patients.

The evolution of valvular disease in antiphospholipid syndrome (APS) is barely known. In order to evaluate whether the presence or absence of valvular disease at the time of diagnosis of APS, assessed by an initial echocardiogram, predicts its subsequent evolution, we performed a prospective cohort study. We included 53 patients with APS. An initial transthoracic echocardiogram was performed on patients at the time of diagnosis of APS. Serial echocardiograms were conducted along a 12-year follow-up. Final echocardiograms were used for comparative purposes. We started with 29 patients (54%) with and 24 (45%) without valvulopathy at initial echo. At the final echocardiogram, 27 of 29 patients with initial valvulopathy continued to have valvular disease (a 93% observed likelihood), and 22 of 24 patients without initial valvulopathy demonstrated an absence of valvular disease (a 91% observed likelihood). Patients with valvulopathy in comparison with those without presented more arterial thrombotic events (69% vs. 20%, P < 0.001), atherosclerotic risk factors (62% vs. 29%, P = 0.01), livedo (48% vs. 16%, P = 0.01) and migraine (41% vs. 12%, P = 0.02). We have identified two subtypes of APS patients with and without valvulopathy by defining differential clinical features and with little crossover in valvular involvement over a long follow-up period, giving a high prognostic value to the initial echocardiographic assessment.

DNase 1 activity in patients with systemic lupus erythematosus: relationship with epidemiological, clinical, immunological and therapeutical features.

The main objective of this study is to determine the relationship between the activity of DNase1 and the clinical and immunological features in patients with systemic lupus erythematosus (SLE). A total of 66 patients (8 men and 58 women) diagnosed with SLE according to the American College of Rheumatology (ACR) SLE classification criteria were included in the study. Sixty-two sera from healthy blood donors were also included as controls. Epidemiological, clinical, immunological and therapeutical features for each patient were obtained. Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). DNase1 activity was determined by using a radial enzyme diffusion method. Statistical analysis was performed using SPSS 12.0 software, with significant P value <0.05. Dnase1 activity was lower in patients with SLE than in the control group: 13.69 +/- 8.52 mug/mL vs 24.75 +/- 12.32 mug/mL, respectively (P < 0.005). No statistical relationship was found between DNase1 activity and disease evolution time, hypertension, presence of absolute or relative proteinuria, SLEDAI, new clinical manifestations, anti-Ro antibodies, anti-La antibodies, anti-RNP antibodies, anti-DNA antibodies, anti-cardiolipin antibodies, lupus anticoagulant, or with the treatment pattern received by the patients. Although important differences in DNase1 activity were found between patients with or without anti-Sm antibodies, they did not reach statistical significance. DNase1 activity was significantly lower in patients with SLE. Nevertheless, we did not find further relationships with any other of the epidemiological, clinical, immunological or therapeutical variables considered.

Anti-PDGFR-alpha antibodies measured by non-bioactivity assays are not specific for systemic sclerosis.

OBJECTIVE: To evaluate the presence of anti-PDGFR-alpha antibodies by immunological methods in patients with systemic sclerosis (SSc). METHODS: Fifty-eight women diagnosed with SSc and 36 healthy women controls were included. IgG anti-PDGFR-alpha were measured by ELISA and immunoblot. Associations with clinical and immunological findings were also studied. RESULTS: Non-significant differences were detected between patients with SSc and controls: median value 0.287 (range 0-2.06) versus median value 0.226 (range 0-2.94), respectively (p = 0.583). No correlation between the presence of anti-PDGFR-alpha antibodies and clinical and serological features was found. Serum samples from patients with SSc and healthy people who had high titres of anti-PDGFR-alpha antibodies by ELISA recognised the same band corresponding to PDGFR-alpha by immunoblot. CONCLUSION: Although anti-PDGFR-alpha antibodies seem to be disease-specific when determined by bioactivity assays, these antibodies are also detected in normal subjects when immunological methods are used. Thus, anti-PDGFR-alpha antibodies may arise from natural autoantibodies. Possibly, SSc autoantibodies recognise a different epitope on the PDGFR-alpha molecule which triggers its stimulatory effect when analysed by functional assays. Alternatively, naturally occurring autoantibodies may even become pathogenic after affinity maturation and class switching in genetically susceptible subjects.

Activation of the signal transducer and activator of transcription-1 in diffuse proliferative lupus nephritis.

Difuse proliferative lupus nephritis (DPLN) is the most common and severe form of lupus nephritis. A predominance of IFN-gamma-producing T cells in both peripheral and renal tissues of patients with DPLN has been identified which suggests an important role for cell-mediated immunity in the pathogenesis of this complication in SLE. The biological effects of IFN-gamma rely mainly on the activity of the transcription factor called signal transducer and activator of transcription (STAT)-1. To assess the IFN-gamma/STAT-1 pathway in DPLN, we examined the expression of STAT-1 in renal biopsies from 15 DPLN patients by immunohistochemical staining with an anti-STAT-1 antibody. The expression of STAT-1 in renal tissues was correlated with several clinical and laboratory findings in these DNPN patients.STAT-1 was activated in the tubular cells in all DPLN patients. Seven of 15 DPLN biopsies (46.7%) showed positive cells in glomeruli. Five of these seven DPLN biopsies (71.4%) with positive glomerular cells showed a serum creatinine >1.5 mg/mL at the time the biopsy was carried out whereas only one of eight DPLN biopsy specimens (12.5%) without positive glomerular cells, showed a serum creatinine >1.5 mg/mL (P = 0.041). Moreover, the percentage of DPLN patients with a worse renal outcome in those who showed expression of STAT-1 in glomerulari were higher in comparison to those without STAT-1 expression (P = 0.041). Our results show that STAT-1 is activated in DPLN suggesting that biological effects of IFN-gamma in renal tissues depend, at least in part, on the activation of STAT-1.

Opposed independent effects and epistasis in the complex association of IRF5 to SLE.

Genetic variation in the interferon regulatory factor 5 (IRF5) gene affects systemic lupus erythematosus (SLE) susceptibility. However, association is complex and incompletely defined. We obtained fourteen European sample collections with a total of 1383 SLE patients and 1614 controls to better define the role of the different IRF5 variants. Eleven polymorphisms were studied, including nine tag single nucleotide polymorphisms (SNPs) and two extra functional polymorphisms. Two tag SNPs showed independent and opposed associations: susceptibility (rs10488631, P<10(-17)) and protection (rs729302, P<10(-6)). Haplotype analyses showed that the susceptibility haplotype, identified by the minor allele of rs10488631, can be due to epistasis between three IRF5 functional polymorphisms. These polymorphisms determine increased mRNA expression, a splice variant with a different exon 1 and a longer proline-rich region in exon 6. This result is striking as none of the three polymorphisms had an independent effect on their own. Protection was independent of these polymorphisms and seemed to reside in the 5' side of the gene. In conclusion, our results help to understand the role of the IRF5 locus in SLE susceptibility by clearly separating protection from susceptibility as caused by independent polymorphisms. In addition, we have found evidence for epistasis between known functional polymorphisms for the susceptibility effect.

Multiplex family-based study in systemic lupus erythematosus: association between the R620W polymorphism of PTPN22 and the FcgammaRIIa (CD32A) R131 allele.

A functional polymorphism in PTPN22, a gene encoding a phosphatase involved in T-cell signaling, has been associated with autoimmunity. We checked for the prevalence of the PTPN22 R620W polymorphism in multiplex families affected with systemic lupus erythematosus (SLE) and other autoimmune diseases. Its association with other polymorphisms in mannose binding lectin (MBL) and FcgammaRIIa (CD32A) genes was also studied. Deoxyribonucleic acid samples were obtained from 233 Spanish individuals who belonged to 21 families in which at least two members had been diagnosed with some autoimmune disease, mainly SLE. A healthy control population was also included (n= 129). Genotyping for the R620W single-nucleotide polymorphism (SNP) was performed by restriction fragment length polymorphism analysis of polymerase chain reaction products. Allele frequency for the T allele was slightly higher in the families with autoimmune disease, especially when considering the affected individuals (0.094 vs 0.062). Actually, 18.8% affected family members vs 11.6% controls had the polymorphism (P= 0.179). Nineteen percent of affected individuals had both the PTPN22 T and the CD32A R131 alleles, whereas only 8.5% unaffected relatives had both susceptibility alleles simultaneously [P= 0.031, odds ratios 2.508 (95% confidence interval 1.066-5.896)]. The tendency toward finding the T allele more frequently in members affected with some particular autoimmune disorder suggests that this SNP may confer susceptibility to autoimmunity. The fact that more affected than unaffected relatives carried both the T and the R131 alleles simultaneously leads us to think about the existence of a combinatorial effect between genes that could help define individuals prone to autoimmune diseases.

Lack of association of the PTPN22 gene polymorphism R620W with systemic sclerosis.

OBJECTIVE: It has recently been reported that some autoimmune diseases seem to be associated with a functional polymorphism in PTPN22, a gene which encodes a phosphatase known to be important in T-cell signaling. The aim of our study was to check for the prevalence of the PTPN22 R620W polymorphism in patients with systemic sclerosis. METHODS: DNA samples from 54 systemic sclerosis patients and 55 healthy controls were obtained from peripheral blood and genotyping was performed by means of a restriction fragment length polymorphism analysis of PCR products (RFLP-PCR). RESULTS: Allele frequency for the T allele was slightly higher in the patients group (0.074 versus 0.055). Eight out of the 54 systemic sclerosis patients (14.8 %) were heterozygous for this single nucleotide polymorphism whereas the CT genotype was found in 6 out of the 55 controls (10.9%). Nevertheless, the difference did not reach statistical significance (p = 0.542). Neither certain antibodies linked to systemic sclerosis (anti-centromere and anti-topoisomerase I antibodies) nor any particular clinical involvement were associated with the polymorphism. CONCLUSION: This particular single nucleotide polymorphism of PTPN22 does not seem to be associated with systemic sclerosis.

Association of a non-synonymous single-nucleotide polymorphism of DNASEI with SLE susceptibility.

OBJECTIVES: To investigate the association of a non-synonymous single-nucleotide polymorphism (SNP) in DNASEI with susceptibility to systemic lupus erythematosus (SLE) and the production of autoantibodies to nuclear antigens. METHODS: The Gln244Arg (rs1053874) SNP was studied in 276 SLE patients and in 368 healthy controls of Spanish ancestry. Its relationship with SLE susceptibility, serum DNase I activity, anti-ribonucleoprotein (RNP), anti-double-stranded DNA (dsDNA), anti-nucleosome and anti-single-stranded DNA (ssDNA) antibodies was determined. RESULTS: An association of the Gln244Arg SNP with SLE susceptibility that followed a recessive genetic model (P=0.002) was found. The GG genotype was more common in SLE patients (59.8%) than in controls (47.3%). However, the Gln244Arg genotype did not correlate with DNase I activity in sera from SLE patients or from controls. In addition, the Gln244Arg SNP did not influence autoantibody titres significantly. CONCLUSION: The association of the Gln244Arg SNP with SLE susceptibility indicates that common polymorphisms in DNASEI play a role in the genetics of SLE. However, the lack of effect of the Gln244Arg SNP on serum DNase I activity calls into question the direct involvement of this specific SNP.

Chronic intestinal pseudo-obstruction associated with biliary tract dilatation in a patient with systemic lupus erythematosus.

We present the case of a 57-year old female patient diagnosed with systemic lupus erythematosus (SLE) along with glomerulonephritis and chronic intestinal pseudo-obstruction (CIPO). Dilatation of bile and pancreatic ducts not associated with malignant or litiasic obstruction is reported. The combination of bile duct associated with CIPO in a patient with lupus has not been previously reported in the literature and it probably suggests a smooth muscle dysmotility.

Predictors of poor renal outcome in patients with lupus nephritis treated with combined pulses of cyclophosphamide and methylprednisolone.

Lupus nephritis remains a major cause of morbidity and mortality in patients with systemic lupus erythematosus. Although the renal prognosis has improved, the optimal therapeutic regime has not been definitively established, and significant challenges remain in the management of disease progression and recurrent renal relapse. We performed a prospective study to evaluate the outcome of 38 patients with severe lupus nephritis treated with standard cyclophosphamide and methylprednisolone pulse therapy, and to determine the variables associated with poor outcome. Five patients developed end-stage renal disease (ESRD) (13%), 10 (26%) developed persistent proteinuria (> 1 g/24h) and 15 (39%) suffered at least one relapse after 8 years of follow-up. A high chronicity index, interstitial fibrosis (P = 0.04), persistent hypertension (P < 0.0001) and hypocomplementaemia (P = 0.002) after treatment were the major variables associated with ESRD. Tubular atrophy (P = 0.01), persistent hypertension (P = 0.0001) and hypocomplementaemia after treatment (P = 0.0281) were associated with persistent proteinuria. Persistence of anti-dsDNA antibodies and hypocomplementaemia after treatment (P = 0.0118) were associated with renal relapse. Our data suggest that the group of patients with persistence of hypocomplementaemia and raised anti-dsDNA antibodies titres are at high risk of renal relapse and may be candidates for continuation of immunosuppressive treatment. Patients with persistent proteinuria alone or a high chronicity index are less likely to respond to immunosuppression, and strict control of the hypertension may be the best approach.

Antiphosphatidylethanolamine antibodies contribute to the diagnosis of antiphospholipid syndrome in patients with systemic lupus erythematosus.

OBJECTIVE: To evaluate the correlation between antiphosphatidylethanolamine antibodies (aPE) and some antiphospholipid antibodies (aPL)-related clinical manifestations in patients with systemic lupus erythematosus (SLE). METHODS: Patients with SLE (n=217) were tested for the presence of aPE, anticardiolipin antibodies (aCL), and lupus anticoagulant (LA). The prospective aPL-related clinical manifestations studied were: thrombosis, thrombocytopenia, recurrent fetal losses, heart valvulopathies, hemolytic anemia, livedo reticularis, and pulmonary hypertension. RESULTS: A total of 109 SLE patients (50.23%) were IgG aPE-positive; 17.51% presented aPE as the sole autoantibody and had some clinical features of aPL-related clinical manifestations. IgG aPE were associated to the presence of heart valvulopathies (p=0.002). A statistical difference was also found when considering high levels of IgG aPE (O.D.>0.600) in patients with livedo reticularis (p=0.008). CONCLUSION: The evaluation of IgG aPE may allow us to detect some more patients with aPL-related clinical manifestations in the SLE population, aPE correlated particularly with valvulopathies and livedo reticularis.

Mannose binding lectin and FcgammaRIIa (CD32) polymorphism in Spanish systemic lupus erythematosus patients.

OBJECTIVE: Mannose binding lectin (MBL) and FcgammaRII (CD32) polymorphisms have both been implicated as candidate susceptibility genes in systemic lupus erythematosus (SLE). The aim of this study was to evaluate the relationship of these polymorphisms with SLE. METHODS: We studied a cohort of 125 SLE patients from Barcelona, Spain and 138 geographically matched controls. Sequence-specific primer-polymerase chain reaction (SSP-PCR) amplification was used to determine CD32 and MBL structural polymorphisms. MBL haplotypes were established using sequence-specific oligonucleotide probing techniques. RESULTS: Patients carried the MBL codon 54 mutant allele more frequently than controls [odds ratio (OR) 2.2; 95% confidence interval (CI) 1.2-4.0; P=0.007] and the haplotype HY W52 W54 W57 was found to be significantly lower in cases compared with controls (OR 0.6; 95% CI 0.4-0.9; P=0.016). CONCLUSION: The MBL gene codon 54 mutant allele appears to be a risk factor for SLE, whilst haplotypes encoding for high levels of MBL are protective against the disease. Differences between controls and patients were not significant when considering the FcgammaRIIa polymorphisms; similar results were observed for renal affectation.

A simplified technique for determining the sensitivity of cytomegalovirus strains to ganciclovir.

A technique for determining the susceptibility to ganciclovir of cytomegalovirus (CMV) strains isolated in clinical samples is described. The inoculum was composed of a partially infected suspension of cells from a young positive culture (< 10 days), usually the first passage of the primary culture. The appropriate dilution of the cell suspension to provide a suitable inoculum was based on a previous study of five strains grown in different dilutions which provided a countable number of plaques and avoided titration of each of the isolated strains. Fifty-three strains were studied at three different dilutions. Five from patients on maintenance ganciclovir therapy with poor clinical response had a 50% inhibitory dose (ID50) between 21.46 and 13.35 microM and the remainder an ID50 between 2.31 and 10.5 microM, comparable to results obtained by other authors using susceptibility techniques with a sonicated inoculum. Three of these strains were studied by both methods using sonicated inoculum and cell suspension inoculum. The mean time which elapsed between seeding the specimen and obtaining sensitivity was 39.00 and 27.66 days, respectively. The technique reduces significantly the time involved since relatively young cultures can be studied and previous titration is not required.