IgG subclasses in pemphigus vulgaris

Amrinder J Kanwar, Gurvinder P Thami, Gursharan K Bedi

 Department of Dermatology and Venereology, Government Medical College, Chandigarh-160047, India

Correspondence Address:
Amrinder J Kanwar
Department of Dermatology and Venereology, Government Medical College, Chandigarh-160047
India

Introduction

In pemphigus autoantibodies directed against the cell surface of keratinocytes can be demonstrated in serum by indirect immunofluorescence and in epithelium by direct immunofluorescence (DIF).[1][2] DIF is most reliable diagnostic test in pemphigus and remains positive for many years after clinical remission.[3] The circulating antibodies, are always of IgG type, however in bound antibodies, IgG is almost invariably present and in about half of the patients there are deposits also of IgA, IgM or C₃.[4] Further analysis of IgG subclasses responsible for pathogenesis of pemphigus have shown IgG₁ and IgG₄ as predominant subclasses deposited in intercellular spaces.[5][6][7] The aim of the present study was to characterize IgG subclasses in DIF in Indian patients of pemphigus vulgaris and their correlation, if any, to the activity or severity of the disease.

Materials and Methods

Irrespective of age, sex, extent and duration of disease, 13 Indian patients of pemphigus vulgaris diagnosed clinically and histopathologically were taken for study of IgG subclasses.

The disease was active in all patients and they were at variable stage of therapy with dexamethasone-cyclophosphamide pulse. DIF was positive and showed deposition of IgG in intercellular spaces. IgG subclasses were looked for in immunofluorescence specimens using standard immunofluorescence techniques.

Results

In all there were 10 males and 3 females with age range of 12-56 years. Prescence of IgG subclasses was graded as absent(-), weakly positive(+/-), positive(+), strongly positive(++), very strongly positive(+++). Details are shown in [Table - 1].

IgG₁ and IgG₄ were the most frequently deposited subgroups with very strongly positive reaction seen only with IgG₄ deposition. Eleven patients (84.6%) had both IgG₁ and IgG₄ deposits. One patient each was negative for IgG₁ and IgG₄. IgG₂ was detected in 6 patients (46.1%) and IgG₃ was found in 2 patients (15.3%) only. No correlation between age, sex, severity or extent and activity of the disease with type of IgG subclasses was found.

Discussion

Pemphigus in Indians is peculiar in that onset of the disease occurs at a younger age and pemphigus vulgaris is the most common variant while pemphigus foliacious is uncommon.[7] Despite these clinical differences, it is immunopathologically same as in other countries. Wilson et al (1992) have confirmed these findings while comparing immunofluorescence studies of Indian and UK population.[7] Previous studies have demonstrated that it is IgG₁ and IgG₄ fractions which are predominantly deposited in DIF of pemphigus.[5-7] These studies have failed to find a correlation with clinical parameters like type, severity or activety of the disease as in the present study. Subclasses IgG₃ and IgG₂ has not so far been found to the extent as in the present study. Wilson et al reported IgG₂ in (11.1%) and IgG₃ in none of the 19 Indian patients studied.[7] The present study emphasises the previous findings that IgG subclasses are not related to type, extent or severity disease in pemphigus vulgaris and that pemphigus vulgaris in Indians is at least not different immunologically.

Acknowledgement

We are thankful to Dr Vijay Kumar of School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York for help in carrying out immunofluorescence studies.

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