Xref: utzoo sci.med:7719 sci.bio:1581
Path: utzoo!utgpu!attcan!uunet!nih-csl!jim
From: jim@nih-csl.UUCP (jim sullivan)
Newsgroups: sci.med,sci.bio
Subject: Re: rH factor
Message-ID: <819@nih-csl.UUCP>
Date: 10 Nov 88 17:31:52 GMT
References: <760@stolaf.UUCP>
Reply-To: jim@nih-csl.UUCP (jim sullivan)
Organization: NIH-CSL
Lines: 29
Keywords:

In article <760@stolaf.UUCP> rabe@stolaf.UUCP (The Love Pooka) writes:
>The rH factor is a set fo surface antibodies on erythrocytes (red blood 
>cells).  The designation positive or negative is based on whether or not
>the mother has passed these set of antibodies on to her child(ren).  Someone
>who possesses these antigens is rH positive.
>
>A person who is negative CAN become positive when positive blood is transfused
>into his/her body.  This is sensitization. 
>I made a mistake.  It is possible for the father to contribute as well.
>It is NOT possible to go from rH positive to rH negative.
>I'll quit now.

I think "The Love Pooka" is confusing rH positive to mean having antibodies
to the rH antigen.  rH positive means that the red cells in the individual
have the rH antigen on their surface.  A rH positive person (most people)
do not have anibodies to this antigen or their red cells would be attacked.
An rH negative person, since they do not have the antigen on their red cells,
CAN produce antibodies to the antigen.  If rH positive red cells are transfused,
the rH negative person will become sensitized to the rH antigen and develope antibodies.
This does NOT make them rH positive.  It makes them sensitized to the rH antigen.
The danger is when an rH negative mother is carrying a rH positive fetus.
The first pregnancy is usually not a problem because it takes time for the
antibodies to develope but the second pregnancy could result in the mother's
anti-rH antibodies attacking the fetus.

A rH negative individual CANNOT become rH positive.
A rH positive individual CANNOT become rH negative.

Now I'll quit