Re: Are immunoglobulins and antibodies the same thing?

Preecha -
   After doing a bit of hunting around and after asking others, the answer 
seems to be that immunoglobulins and antibodies are interchangable terms.  
In my mind, I think of immunoglobulins as the major class of proteins that 
antibodies belong to based on their overall protein structure.

   Definitions that encompass the above are as follows:
IMMUNOGLOBULIN: large class of glycoproteins that constitute the antibodies 
produced in response to antigenic stimuli.

ANTIBODIES: Immunoglobulin multichain glycoproteins synthesized by B-cells 
and plasma cells (memory cells) in response to the introduction of foreign 
substances.

   In addition, remember that there are different immunoglobulin (Ig) 
classes (IgA, IgG, IgM, IgE, and IgD) that will produce different 
antibodies, each with specialized functions (due in part to structure) and 
specificity for an antigen. 

   I couldn't find any answer that definitively stated any major 
differences between the two. You could think of an antibody being generated 
against a given antigen during a vaccination (i.e. diptheria toxoid).  The 
antibody produced by the B cells (and memory cells over time) will 
specifically recognize diptheria toxin; in addition, the antibody produced 
by B cells will belong to the IgG class (in general). One could also think 
of immunoglobulins in a generic sense - where many different antibodies 
produced by B-cells make up a population of an immunoglobulin class, for 
example, IgG, that is present at any one time in the body.

  
REFERENCES:

Roitt et al. Immunology, 5th ed. 1998.

Ryan et al. Sherris Medical Microbiology, 3rd ed. 1994

   Sorry that I don't really have a specific answer, but I do hope that 
what I did provide will be useful!  Best of luck!

     Glynis
     Rutgers University