43. A 5-year-old boy with a history of recurrent ear infections receives his preschool booster immunization against diphtheria-tetanus-pertussis. He is participating in a community-sponsored study to determine the humoral immune response to tetanus toxoid (tt). His response is well below normal for age- and sex-matched children. Peripheral B lymphocyte count and T lymphocyte count and function are within the reference range. The antibody he makes is positive in both the passive hemagglutination and complement-mediated lysis of tt-coated erythrocytes. His antibodies do not opsonize tt-coated latex particles for phagocytosis and do not directly precipitate tt efficiently. This child most likely has a defect in which of the following processes? A) Affinity maturation of immunoglobulins B) Immunoglobulin isotype switching C) Recombination of heavy chain variable region genes D) Recombination of light chain variable region genes E) Somatic mutation of immunoglobulin genes
spjokes Forum Senior
Topics: 3 Posts: 88
06/18/06 - 04:40 PM
#2
?? A
robin082006 Forum Hero
Topics: 471 Posts: 5,125
06/18/06 - 10:41 PM
#3
B ___________________ The Key to Succeed is Patience.
sridevibandaru24 Forum Guru
Topics: 33 Posts: 434
06/20/06 - 07:25 PM
#4
B
raves Forum Elite
Topics: 21 Posts: 219
06/23/06 - 01:48 PM
#5
b??COS NO IgG?? ___________________ 'NISCHAY KAR APNI JEET KARO'
