Tag Archives: IgG1

The molecular basis of disease heterogeneity in autoimmune conditions such as Pemphigus vulgaris is poorly understood. Although desmoglein 3 (Dsg3) has been well established as a primary target of immunoglobulin (Ig) autoantibodies in PV, there remain several questions regarding the overall distribution of anti-Dsg3 Ig subtypes among patient subsets and considerable controversy regarding whether an isotype switch can be observed between phases of disease activity. To systematically address the outstanding questions related to Ig-isotype specificity in PV, we analyzed IgA, IgM, IgG1, 2, 3 and 4 anti-Dsg3 levels by ELISA in 202 serum samples obtained from 92 patients with distinct clinical profiles based on a set of defined variable (activity, morphology, age, duration) and constant (HLA-type, gender, age of onset) clinical parameters, and 47 serum samples from HLA-matched and -unmatched controls. Our findings provide support for earlier studies identifying IgG4 and IgG1 as the predominant antibodies in PV with significantly higher levels in active than remittent patients. We do not see evidence for an isotype switch between phases of disease activity and remission, and both IgG4 and IgG1 subtypes remain elevated in remittent patients relative to controls. We do, however, find IgG4 to be the sole subtype that further distinguishes PV patient subgroups based on different disease morphologies, disease duration, and HLA-types. These data provide further insight into the immune mechanisms responsible for phenotypic expression of disease, and contribute to the broader effort to establish comprehensive immunoprofiles underlying disease heterogeneity to facilitate increasingly specific and individualized therapeutic interventions.

Full article available at: http://www.ncbi.nlm.nih.gov/pubmed/22779708

Pemphigus is a chronic, muco-cutaneous autoimmune blistering disorder; two main variants being pemphigus vulgaris (PV) and pemphigus foliaceus (PF). PV is the most common subtype, varying between 75 to 92% of total pemphigus patients. Although no community based studies are undertaken to estimate the incidence of pemphigus in India, it is relatively common. A questionnaire based survey in Thrissur district of south India estimated pemphigus incidence to be 4.4 per million population. Mortality due to pemphigus has decreased remarkably with the aggressive and widespread use of corticosteroids, prior to which it was as high as 90%. High dose corticosteroids were once used in combination with other immunosuppressants with good improvement, but such high doses of corticosteroids were often associated with severe side effects, and were responsible for the death of nearly 10% of the patients. With the aim of reducing the adverse effects of long term, high dose steroid administration dexamethasone cyclophosphamide pulse (DCP) therapy was introduced in 1984. Since then DCP or oral corticosteroids with or without adjuvant immunosuppressants (azathioprine, cyclophosphamide, mycophenolatemofetil, and cyclosporine) have been the corner-stone of therapy for these disorders in India. Despite the benefits associated with DCP therapy compared to high dose oral steroids, it cannot be denied that even DCP therapy with or without adjuvants can lead to numerous adverse events, which account for majority of deaths in pemphigus. Moreover there are few patients who fail to improve with these conventional treatments or have contraindications for their usage. Thus there has been a constant search for newer therapeutic modalities in pemphigus. Rituximab (Reditux. Dr. Reddy’s, Hyderabad, India and MabThera TM , Roche, Basel, Switzerland), a monoclonal chimeric IgG1 antibody targeting the B cell specific cell-surface antigen CD20, is one such newer novel therapy for pemphigus (an off-label indication for its use. It has so far been approved by FDA for use only in CD 20+ B cell non-Hodgkin’s lymphoma, treatment resistant rheumatoid arthritis, Wegener’s granulomatosis and microscopic polyangiitis).

There is currently no consensus on the optimal dosage and schedule of rituximab in treatment of pemphigus. The various treatment protocols followed include:

  1. Lymphoma protocol- Most commonly followed protocol. Rituximab is administered at a dose of 375mg/m 2 body surface area weekly for four weeks.
  2. Rheumatoid arthritis protocol- Two doses of rituximab 1g is administered at an interval of 15 days. Increasingly used by dermatologists and is the protocol currently followed in our institute. Advantage over the lymphoma protocol include less cost and fewer infusions.
  3. Combination therapy- Rituximab has been used in combination with IVIG, immunoadsorption and dexamethasone pulse therapy
  4. Long-term rituximab treatment with regular infusions every 4 or 12 weeks following an induction cycle of infusions every week

Full article can be viewed at: http://www.ijdvl.com/article.asp?issn=0378-6323;year=2012;volume=78;issue=6;spage=671;epage=676;aulast=Kanwar