• Function of HLA Antigens

• Category 1 Immunological Problems: HLA Compatibility as a Cause for Recurrent Spontaneous Pregnancy Loss

• Category 2 Immunological Problems: Autoantibody Response to Phospholipid Adhesion Molecules

• Category 3 Immunological Problems: Autoimmune Response to Nuclear Components

• Category 4 Immunological Problems: Autoimmune Response to Sperm Antigen

• Category 5 Immunological Problems

  • Chapter 1: CD 56+ Natural Killer Cells

  • Chapter 2: CD 19+ 5+ B Cells (1)

  • Chapter 3: CD 19+ 5+ B Cells (2)

All cells of the body have on their surfaces proteins or peptides called HLA (human leukocyte antigens). These are depicted in the figure below. These antigens serve as antennae or "fly paper" that recognize and capture foreign interlopers--such as germs, viruses or cancer cells--that get into our bodies. With the new captured information, these cells signal the immune system to make antibodies (IgM, IgG and IgA) against the germ, virus or cancer cell.

HLA Antigens: serve as antennae to recognize foreign germs or viruses entering the body. Communicate this information to the white blood cells to initiate an immune response.

A pregnancy must also be recognized as a foreign being (father puts HLA antigens on the placenta that are different from those of the mother). When this applies, the mother makes an antibody called a blocking antibody that attaches to the placenta and makes it look to her like a "wolf in sheep's clothing." The antibody she makes in this circumstance does not kill; it protects the baby and makes the placental cells grow faster.

When the father's HLA antigens placed on the placenta are too similar to the mother's HLA antigens, she does not make the antibody. In this circumstance the baby is not protected, the placental cells are not stimulated to grow and the baby dies. She interprets the pregnancy as "altered self" (i.e., a cancer cell). Therefore, when the cells of the baby die, she activates other immune problems from Category 2, 3, 4 or 5 where the natural killer cells that she was born with are now misinterpreting the baby as a cancer. This occurs in couples sharing DQ alpha HLA antigens.

Immune Response to Pregnancy (Alloimmunity)

• Function: to alert the mother to react to the baby as a baby, not as an infection.
  
• Consequence: blocking antibody production (crossmatch positive by flow cytometry).
  

Immune Response to Infection (Infectious Immunity)

• Consequences: antibody production (gamma globulins) that destroys the germ or virus and remains in the body as a memory if the germ or virus returns.