Infants Born with the Immunodeficiency Disease X-Linked Agammaglobulinemia (XLA) Have

Infants born with the immunodeficiency disease X-linked agammaglobulinemia (XLA) have a block in B cell development, and fail to produce mature B cells. As a result, these infants lack the ability to produce antibodies. After birth, babies with XLA first begin to show symptoms of recurrent and persistent extracellular bacterial infections due to common environmental pathogens when they are 4-6 months of age. The reason these infants are healthy for the first 4-6 months after birth is because:Newborn infants have high circulating levels of maternal IgG at birth.

A) Newborn infants are not exposed to bacterial pathogens for the first 4-6 months of life.
B) Newborn infants are born with high circulating levels of complement proteins to protect them.
C) Newborn infants are born with high circulating levels of antimicrobial peptides to protect them.
D) Newborn infants are vaccinated against these common bacterial pathogens.
10-18 High-affinity IgG and IgA antibodies can neutralize toxins and block the infectivity of viruses and bacteria