OB-GYN-L Messages for March, 2006: Re: Antenatal Rhogam

Re: Antenatal Rhogam
From: Terrence.Jones@kp.org
Fri Mar 24 20:23:07 2006

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Sorry Dean, I don't have any re*v*erence.
On the topic of "sensibilization", that Dan brought up, it would be nice to have some reference (Dr. Bowman, maybe?) that demonstrates that low levels of passive immune AB "leads to" sensibilization. In this setting, it is correct that AB levels are (relatively) low, but it is low level B cell response that it refers to. Think this was addressed by Ken Moise when answering Geff's inquiry re: Pt with neg titre and Rec'd RHIg at prior delivery, then presents sensitized in subsequent preg. The concept is the B cell's been primed, but AB prodxn is below the limits of detection. With subsequent exposure, there is augmented (anamnestic) response. Search the ob/gyn.net archives for April 7, 1998 and scroll to the responses per Dr. Moise. Would like to see the ref that states that "sensibilization" as an entity in itself, is a consequence of a specifically low passive AB titre, and not simply antigen excess, which can occur in the absence of any passive immunization?
Think the current assessment is there are many factors responsible for AMIS (antibody mediated immune suppression) with RHIg - and, as Bob says, there appears to be a threshold effect for the coaggregation of BCR (B cell receptor) and Fc fraction of RHIg which downregulates the B-cell (Kumpel (2002) Immunology Letters 82:67-73). Tho even low levels of Fc appear to be effective (Preissler (2005) Immunol Invest 34:53-70). The molar concentrations of RHIg to D+ RBC in this setting is not as impt as in FMH. Instead, there is an absolute number of epitope bound sites, on individual fetal RBC's, that must be achieved in order to accomplish sufficient suppressive coaggregation.
(struggling for relevance, if not reverence) /tj
CONFIDENTIAL OR PRIVILEGED: This communication contains information intended only for the use of the individuals to whom it is addressed and may contain information that is privileged, confidential or exempt from other disclosure under applicable law. If you are not the intended recipient, you are notified that any disclosure, printing, copying, distribution or use of the contents is prohibited. If you have received this in error, please notify the sender immediately by telephone or by returning it by reply email and then permanently deleting the communication from your system. Thank you.
zygote@icsi.net Sent by: ob-gyn-l@obgyn.net 03/24/2006 05:21 PM Please respond to ob-gyn-l
To: Multiple recipients of list OB-GYN-L <ob-gyn-l@dns.obgyn.net> cc: Subject: Re: Antenatal Rhogham
The concept is referred to as immunological enhancement and has been stated for many years. Small volumes of Ab bind with hapten and instead of destruction and removeal from circulation are processed with primary immune response as result with formation of endogenous Rh ab.
It is better to have excess antibody that two little ab. As someone who has published and does IUT's for really sick alloimunization with severe anemia - no fun! Prevention is better.
Hope this helps - reference exists but have not loked for it for years!
Bob
On 24 Mar 2006 at 18:39, Dean Huffman . wrote:
Date sent: Fri, 24 Mar 2006 18:39:48 -0600 Send reply to: ob-gyn-l@obgyn.net From: "Dean Huffman ." <dean@thehuffpeople.net> To: Multiple recipients of list OB-GYN-L <ob-gyn-l@dns.obgyn.net> Subject: Re: Antenatal Rhogham
> .
>
> I seem to have heard at one time, although I could never find a printed
> reference, that the time of greatest risk for sensitization is when the
IgG > titers from RhoGam are extrememly low, but not yet absent. Has anybody
else > ever heard this? If so, do you have a reverence?

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 Sorry Dean, I don't have any re*v*erence. On the topic of "sensibilization", that Dan brought up, it would be nice to have some reference (Dr. Bowman, maybe?) that demonstrates that low levels of passive immune AB "leads to" sensibilization. In this setting, it is correct that AB levels are (relatively) low, but it is low level B cell response that it refers to. Think this was addressed by Ken Moise when answering Geff's inquiry re: Pt with neg titre and Rec'd RHIg at prior delivery, then presents sensitized in subsequent preg. The concept is the B cell's been primed, but AB prodxn is below the limits of detection. With subsequent exposure, there is augmented (anamnestic) response. Search the ob/gyn.net archives for April 7, 1998 and scroll to the responses per Dr. Moise.  Would like to see the ref that states that "sensibilization" as an entity in itself, is a consequence of a specifically low  passive AB titre, and not simply antigen excess! , which can occur in the absence of any passive immunization?    Think the current assessment is there are many factors responsible for AMIS (antibody mediated immune suppression) with RHIg - and, as Bob says, there appears to be a threshold effect for the coaggregation of BCR (B cell receptor) and Fc fraction of RHIg which downregulates the B-cell (Kumpel (2002) Immunology Letters 82:67-73). Tho even low levels of Fc appear to be effective (Preissler (2005) Immunol Invest 34:53-70). The molar concentrations of RHIg to D+ RBC in this setting is not as impt as in FMH. Instead, there is an absolute number of epitope bound sites, on individual fetal RBC's, that must be achieved in order to accomplish sufficient suppressive coaggregation. (struggling for relevance, if not reverence)  /tj CONFIDENTIAL OR PRIVILEGED:  This communication contains information intended only for the use of the individuals to whom it is addressed and may contain information that is privileged, confidential or exempt from other disclosure under applicable law.  If you are not the intended recipient, you are notified that any disclosure, printing, copying, distribution or use of the contents is prohibited.  If you have received this in error, please notify the sender immediately by telephone or by returning it by reply email and then permanently deleting the communication from your system. Thank you. <table width0%> <tr valign=top> <td> <td>zygote@icsi.net Sent by: ob-gyn-l@obgyn.net 03/24/2006 05:21 PM Please respond to ob-gyn-l <td>                To:        Multiple recipients of list OB-GYN-L <ob-gyn-l@dns.obgyn.net>         cc:                 Subject:        Re: Antenatal Rhogham</table> The concept is referred to as immunological enhancement and has been stated for many years. Small volumes of Ab bind with hapten and instead of destruction and removeal from circulation are processed with primary immune response as result with formation of endogenous Rh ab. It is better to have excess antibody that two little ab. As someone who has published and does IUT's for really sick alloimunization with severe anemia - no fun! Prevention is better. Hope this helps - reference exists but have not loked for it for years! Bob On 24 Mar 2006 at 18:39, Dean Huffman . wrote: Date sent:                       Fri, 24 Mar 2006 18:39:48 -0600 Send reply to:                   ob-gyn-l@obgyn.net From:                            "Dean Huffman ." <dean@thehuffpeople.net> To:                              Multiple recipients of list OB-GYN-L <ob-gyn-l@dns.obgyn.net> Subject:                         Re: Antenatal Rhogham > . > > I seem to have heard at one time, although I could never find a printed > reference, that the time of greatest risk for sensitization is when the IgG > titers from RhoGam are extrememly low, but not yet absent. Has anybody else > ever heard this? If so, do you have a reverence? 

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