> > From: Joy Anderson <[log in to unmask]>
>>
>> regards to immunology (but did study it in my
>> graduate diploma of medical technology many years ago), but my
>> understanding is that IgG is the small immunoglobulin that passes
>> across the placenta (as you stated - classic example is anti-Rh), but
>> that IgA is the one for all 'secretory' purposes, such as milk, lung
>> lining, etc - it has a J-chain joining the two parts that are each
>> like IgG molecules, and this J-chain results in the whole molecule
>> being resistent to degradation (hence it survives in 'hostile'
>> environments like a baby's gut).
>>
>> IgM, on the other hand, is a *huge* molecule that I thought could not
>> get into milk *or* across the placenta.
>>
>> I thought that milk contains nearly all IgA except for the people who
>> are genetically IgA-deficient, and they seem to compensate by having
>> IgG in their milk. (Still not IgM.)
>
>Thanks so much for contributing to this discussion.
>
>I've been doing a fair bit of research and have come across numerous
>references to breastmilk containing mostly IgA but containing all five
>classes of immunoglobin. (IgG, IgA, IgM, IgD and IgE.) The Latrobe U tables
>detailing antibacterial and antiviral properties of breastmilk contain
>references to IgM. http://www.latrobe.edu.au/microbiology/table1.html
>
>There are also lots of references to Secretory IgM, but I don't know enough
>about immunology to know if this is relevant.
>
>-- Jodine Chase

Thanks, Jodine. And thanks for the leads via the web. Very interesting.

 From the refs on the websites (La Trobe and Medscape - linked from
the La Trobe site), there is no IgE, and only small amounts of
anything other IgA. A part quote:

>Breastfeeding: Unraveling the Mysteries of Mother's Milk
>from Medscape Women's Health eJournal[TM]
><snip>
>Secretory immunoglobulin A (sIgA), dimeric IgA coupled to the
>secretory component, is the main immunoglobulin in human milk. IgG
>and IgM are also present in milk, but at much lower concentrations.
>The changing concentration of these immunoglobulins in milk provides
>an example of the interaction between milk components and the
>functional development of the infant: while IgG and IgM rise rapidly
>after birth, the newborn maintains low levels of endogenous IgA
>during the first year of life. IgA is produced in the mammary gland
>in B cells, which originate at maternal sites of high environmental
>pathogen exposure (eg, the small intestine or respiratory tract),
>and therefore protects the infant against pathogens present in the
>immediate environment.

 From this it may be assumed that IgM appearing in any significant
quantity in the baby's serum would be of infant origin, not from milk
- yes?

You mention 'Secretory IgM'. Please can you give me refs for this? I
am not familiar with this type at all, but admit that my immunology
knowledge is many years old.
******************************************************************
Joy Anderson B.Sc. Dip.Ed. Grad.Dip.Med.Tech. IBCLC
Australian Breastfeeding Association counsellor
Perth, Western Australia.   mailto:[log in to unmask]
******************************************************************

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