These results indicate that MCV IgM levels, unlike MCV IgG levels, are not significantly correlated to MCC

These results indicate that MCV IgM levels, unlike MCV IgG levels, are not significantly correlated to MCC. To determine if the MCV EIA measures specific MCV antibodies, competition studies using BKV and MCV VLP were performed on 4 MCV-positive MCC sera and 8 reactive blood donor sera (Fig. prevalence increases from 50% among children age 15 years or younger to 80% among persons older than 50 years. We did not find evidence for vertical transmission among infants. Although past exposure to MCV is common among all adult groups, MCC patients have a markedly elevated MCV IgG response compared with control patients. Our study demonstrates that MCV is a widespread but previously unrecognized human infection. Keywords: Merkel cell polyomavirus, Merkel cell carcinoma, virus-like particles, enzyme-linked immunosorbent assay, serologic assay Merkel cell carcinoma (MCC) is an uncommon skin cancer frequently having a poor prognosis.1 It most often arises in chronically sun-exposed skin and occurs more commonly than expected among immunosuppressed persons, including AIDS patients, transplant recipients and elderly persons.2 Feng < 0.001 for all comparisons). Median MCV EIA values (Fig. 2= 0.25C0.91). Although the SLE patient sera had previously been found to have high rates of nonspecific reactivity to other infectious agents on EIA testing,14 we found no evidence for nonspecific reactivity using the MCV VLP-based EIA. Open in a separate window Open in a separate window FIGURE 2 (= 0.30). For sera from MCV-positive MCC patients, MCV and BKV VLP IgM levels also were not significantly different from each PF-3635659 other (= 0.32). These results indicate that MCV IgM levels, unlike MCV IgG levels, are not significantly correlated to MCC. To determine if the MCV EIA measures specific MCV antibodies, competition studies using BKV and MCV VLP were performed on 4 MCV-positive MCC sera and 8 PF-3635659 reactive blood donor sera (Fig. 2= PF-3635659 0.007) MCV-negative MCC patients. Exposure to MCV infection was prevalent but significantly less common among asymptomatic blood donors (107 of 166, 64%, < 0.001), commercial donors (63 of 100, 63%, = 0.001) and SLE patients (37 of 50, 74%, = 0.015). Patients with symptomatic MCC have GMFG highly elevated MCV antibody levels compared with MCV seropositive control patients without MCC. Among persons seropositive for MCV antibodies, 9 of 21 (43%) MCV-positive MCC patients had high MCV EIA absorbances (>2.5 OD units) compared with only 16 of 107 (15%, = 0.006) blood donor, 2 of 63 (3%, < 0.001) commercial donor and 1 of 37 (3%, < 0.001) SLE patient sera. These results indicate that while low levels of MCV antibodies, indicative of past MCV infection, are common among adults, very high levels of MCV antibodies are most likely to be found among sera from MCV-positive MCC patients, possibly representing ongoing immune stimulation from infected tumors. To assess changes in MCV antibodies with age, we examined a convenience cross-sectional cohort sample of 150 sera from LCH patients ranging in age from 1 month to 72 years old (Figure 3). None of 6 sera from children 1 year or younger were positive for MCV antibodies. Prevalence of MCV antibody positivity increased to 43% among children aged 2C5 years old (12 of 28 patients; 95% CI, 26C61%) and 49% of children and young adults aged 6C15 years old (26 of 53 patients; 95% CI, 34C59%). This correlation between MCV antibody prevalence and age continued among older LCH patients reaching 80% (12 of 15 patients; 95% CI 47C90%) among LCH patients older than 50 years (chi-squared test for trend with age, < 0.001). Open in a separate window FIGURE 3 Age-dependent prevalence of MCV antibodies among Langerhans cell histiocytosis (LCH) patients. Sera from a cross-sectional cohort of persons with a history of LCH were tested for IgG antibodies using the MCV EIA. Antibodies were absent from children 1 year and younger but increased in an age-dependent manner, reaching 80% prevalence among adults over age 50. Some children as young as 2 years old were strongly reactive on this assay. Discussion Our study is consistent with previous PCR-based tissue surveys. Using a serologic test, we are able to examine comparable tissues (i.e., sera) from cases and controls as well as to assay for past and current MCV exposure. Our results are all consistent with MCV.