What type of infections are B cell/antibody deficiencies typically associated with?

B cell and antibody deficiencies are primarily associated with increased susceptibility to infections caused by encapsulated bacteria, particularly in the sinopulmonary region. This is due to the crucial role that antibodies, specifically immunoglobulin G (IgG) and its subclasses, play in opsonization and clearance of pathogens, especially those that are encapsulated. Individuals with B cell deficiencies often have a higher incidence of recurrent respiratory tract infections, such as sinusitis and pneumonia, which can lead to complications like bronchiectasis over time.

The sinopulmonary infections often manifest due to the inability to mount effective antibody responses to these common pathogens, which include Streptococcus pneumoniae and Haemophilus influenzae. Both of these bacteria are encapsulated and can evade phagocytosis without adequate antibody response, leading to the typical presentation in individuals with B cell/antibody deficiencies.

Other types of infections, such as skin and soft tissue infections, gastrointestinal infections, or bone and joint infections, are not as commonly linked to B cell deficiencies as they are typically characterized by different immune responses. Thus, the association with sinopulmonary infections and bronchiectasis accurately reflects the clinical picture seen in these deficiencies.