A pregnant patient typed as Le(a+b-), but has begun producing anti-Lea. What happened?

Master the CAMLPR Transfusion Test with interactive questions and detailed explanations. Boost your knowledge and ensure you're exam-ready with comprehensive study resources!

Multiple Choice

A pregnant patient typed as Le(a+b-), but has begun producing anti-Lea. What happened?

The situation hinges on how Lewis antigens on red cells can change during pregnancy. Lewis antigens (Lea and Leb) aren’t fixed on the cell surface; they come from circulating glycoproteins and are influenced by factors like secretor status and the hormonal/molecular changes of pregnancy. During pregnancy, Lea expression on red cells can transiently disappear or diminish, so a person who previously showed Lea on their cells may momentarily appear Le(a-b-) or have reduced Lea display. If Lea is no longer expressed on the cells, the immune system can become exposed to Lea antigens in other contexts (such as fetal antigens crossing into maternal circulation). This exposure can lead to the production of anti-Lea antibodies. So, a patient who initially typed as Le(a+b-) but later begins producing anti-Lea is consistent with a temporary loss of Lewis expression during pregnancy, followed by alloimmunization against Lea. The other possibilities are less consistent: a new mutation causing anti-Lea is unlikely, pregnancy does not generally enhance Lea expression, and a typing error would not by itself explain newly formed anti-Lea antibodies.

The situation hinges on how Lewis antigens on red cells can change during pregnancy. Lewis antigens (Lea and Leb) aren’t fixed on the cell surface; they come from circulating glycoproteins and are influenced by factors like secretor status and the hormonal/molecular changes of pregnancy. During pregnancy, Lea expression on red cells can transiently disappear or diminish, so a person who previously showed Lea on their cells may momentarily appear Le(a-b-) or have reduced Lea display.

If Lea is no longer expressed on the cells, the immune system can become exposed to Lea antigens in other contexts (such as fetal antigens crossing into maternal circulation). This exposure can lead to the production of anti-Lea antibodies. So, a patient who initially typed as Le(a+b-) but later begins producing anti-Lea is consistent with a temporary loss of Lewis expression during pregnancy, followed by alloimmunization against Lea.

The other possibilities are less consistent: a new mutation causing anti-Lea is unlikely, pregnancy does not generally enhance Lea expression, and a typing error would not by itself explain newly formed anti-Lea antibodies.

More practice questions