QUESTIONS

1. What is a Langerhans cell?
    
2. What type of hypersensitivity (according to Gell & Coombs classification) do the pemphigus diseases represent?
    
3. If you want an immunofluorescence test done on a skin biopsy, you need to submit the sample in Michel�s transport medium.  What�s the matter with good ole formalin?
   
4. When doing immunofluorescent tests on skin biopsies, what is a �lupus line?�
    
5. All of the diseases in the pemphigus group are typified by bulla formation, where one layer of epidermis lifts off another (forming a �cleft�).  Where does the cleft form for:
   
   a) Pemphigus vulgaris
   b) Pemphigus foliaceous
   c) Pemphiugus erythamtosus
   d) Bullous Pemphigoid
    
6. What are �tombstone cells?�
    
7. In pemphigus foliaceous, when the granular layer splits, there are some granular cells above the cleft stuck to the overlying stratum corneum. These are called:
   
   a) Granular �cling-on�s
   b) Granular romulans
   c) Granular cardassians
   d) Granular ferengi
    
8. In which disease is oral cavity involvement unusual?
   
   a) Pemphigus vulgaris
   b) Pemphigus foliaceous
   c) Bullous pemphigoid
    
9. What is �pemphigus anantholytic factor?�
   
   
   
   
    

ANSWERS

1. A Langerhans cell is an epidermal member of hte monocyte/macrophage series.  Its job is presentation of antigens that have been absorbed through the skin to lymphocytes.
   
   
   
   
    
2. The pemphigus group represents Type II hypersensitivty, where cell mediated immunity actually attacks self cells.
   
   
   
   
    
3. Formalin destroys antigenicity of deposited immuno-reactants (antibodies, complement).  Any fluorescent staining is staining for antibodies and/or complement so formalin would destroy exactly what you are trying to detect.  After your sample is removed from Michel�s medium, it is washed & treated w/fluorscein conjugated anti-dog antibody antibodies (or anti-cat antibody antibodies).  IgG, IgM, or complement are what you want to detect.
   
   
   
   
    
4. All pemphigus types bind immunoglobulins intercellularly and this shows up on staining as above.  Bullous pemphigoid & lupus deposit at the basement membrane. This fluorescence of the basement membrane has been termed a �lupus line.�
   
   It is important to note that this is not at all pathognomonic for lupus.  In humans, normal sun exposed skin will show a lupus line (Posing quite a diagnostic dilemma for MDs).  Pets are not as confusing as they have fur but still 43% of normal foot pad biopsies show IgM fluorescence at the basement membrane & 73% or normal dog nose skin will bind IgM at the basement membrane.
   
   
   
   
    
5. Okay, before you can answer this question, you have to know the layers of epidermal cells & which order they are in.  From the outside moving down the layers are:
   
   Horny Layer (stratum corneum)
   Clear Layer (stratum lucidum)- present only in footpads
   Granular Layer (stratum granulosum)
   Prickle Layer (stratum spinosum)
   Basal Layer (stratum basale)
   Basement Membrane
   
   a) Pemphigus vulgaris:  the cleft is �suprabasilar� meaning it is
       between the prickle & basal layers)
   
   b) Pemphigus foliaceous: smack in the middle of the granular
        layer
   
   c) Pemphigus erythemotosus:  under the stratum corneum
   
   d) Bullous Pemphigoid: Lift off is between the epidermis & the
       dermis
   
   
   
   
    
6. Sounds like something indicating a - GRAVE prognosis - get it? Tombstone? Grave?
   Sorry.
   When the prickle cell layer is lifting off the basal layer in pemphigus vulgaris, the basal cells are left sitting there in a row on the basement membrane & they were thought to look like a row of tombstones.  Hence, tombstone cells are basal cells under the cleft in pemphigus vulgaris.
   
   
   
   
    
7. They really are called Granular �cling-on�s.  (not �Klingons�)
   
   
   
   
    
8. Oral cavity involvement is common & often an early sign of pemphigus vulgaris.
   It is a common but usually a later sign of Bullous pemphigoid.
   It is an uncommon sign of pemphigus foliaceous.
   
   
   
   
    
9. Antibodies are produced against glycocalyx of keratinocytes. This inhibits cellular protein & RNA synthesis & leads to the activation & release of pemphigus acantholytic factor which diffuses into the extra-cellular spaces & actually hydrolyzes the glycocalyx.  This is what leads to acantholysis & blister (bulla) formation.