Seropositivity to anti-phenolic glycolipid-I in leprosy cases, contacts and no known contacts of leprosy in an endemic and a non-endemic area in northeast Brazil

Abstract

The seroprevalence rates of IgM anti-phenolic glycolipid-I (PGL-I) antibodies in four study groups with differing exposure to Mycobacterium leprae in Ceará, Brazil were investigated between March 2005 and August 2006. The first three groups in a high prevalence area included 144 cases of leprosy, their 380 contacts and 317 participants with no known leprosy contact. The fourth group in a low prevalence area consisted of 87 participants with no known leprosy contact living in an area in which no cases of leprosy had been reported in the previous 6 months. Seropositivity and levels of IgM antibodies to PGL-I were investigated using ELISA. The seropositivity levels of anti-PGL-I among the different clinical forms of leprosy cases were 61% for lepromatous, 25% for tuberculoid and 27% indeterminate. The levels of anti-PGL-I antibodies in the endemic area differentiated leprosy cases from non-cases. However, the seropositivity was similar among contact cases (15.8%) and no known leprosy contact cases from high (15.1%) and low (13.8%) prevalence areas. The seropositivity of both contacts and no known contacts was much higher than previously reported among no known contacts in other endemic areas. The study indicates that anti-PGL-I antibodies are not useful as immunological markers of household leprosy contacts and no known leprosy contacts in endemic areas.

Early detection of leprosy by examination of household contacts, determination of serum anti-PGL-1 antibodies and consanguinity

“…Although these studies found no differences in seropositivity rates among HHC of MB and paucibacillary leprosy (PB) lep-MB and paucibacillary leprosy (PB) lepand paucibacillary leprosy (PB) leppaucibacillary leprosy (PB) lepleprosy patients, our results indicated a slight difference in serum anti-PGL-1 IgM seropositivity rates between HHC of MB leprosy patients (56.8%) and of PB leprosy patients (43.1%), especially when comparing I leprosy patients (14%) x LL leprosy patients (29%) (p = 0.03). Similar results were reported by Calado et al (2005), Carbona-Castro et al (2008) and Frota et al (2010). The presence of serum antibodies suggests that the PGL-1 antigen induced a humoral immune response, but these increased antibody concentrations apparently could not block M. leprae multiplication in the host (Kaplan & Chase 1980, Touw et al 1982), as we found that two cases progressed to BT leprosy after one year of followup of these seropositive contacts.…”

“…The phenolic glycolipid antibody (PGL-1), as measured using an enzyme-linked immunosorbent assay (ELISA), is considered to be a relevant marker of leprosy activity (Burgess et al 1988, Zenha et al 2009, Frota et al 2010). The PGL-1 fraction is part of the cell envelope of M. leprae and induces the production of the specific humoral response against PGL-1 detected in patient serum (Hunter et al 1982, Cho et al 1983, Foss et al 1993.…”

Factors associated with seropositivity for APGL-Iamong household contacts of leprosy patients

“…The follow-up of these HC is of extreme importance, since an increase or maintenance of APGL-I levels indicates active subclinical infection (19) (20) (23) . Individual immunologic status could occult clinically detectable signs of leprosy for many years (24) .…”

Insight toward Early Diagnosis of Leprosy through Analysis of the Developing Antibody Responses of Mycobacterium leprae -Infected Armadillos

“…The composition of antigens to include in such a test is not yet clear for leprosy. Rapid tests based solely on PGL-I derivatives have been developed and distributed but are not currently in widespread use and are somewhat restricted by high falsepositive rates within regions where leprosy is endemic and even in regions where it is not endemic (3,4,13,20). Our data indicate that while NDO-BSA can provide early diagnosis in armadillos, this can also be achieved with several protein antigens.…”