A 45 year old female presents with recurrent upper and lower respiratory tract infections associated with the diagnosis of IgG3 subclass and polysaccharide antibody response defect. She was started on IVIgG with favorable response. Three years after the start of infusions, she began to develop recurrent gluteal abscesses requiring surgical drainage. Cultures grew Staphylococcus aureus on several occasions.

Further evaluation of the patient's immune system showed mildly decreased T cell numbers and decreased T cell function. Neutrophil chemotaxis and superoxide function was normal. The patient was found to have a MBL level of 0.0 mg/dl indicating she was homozygous for MBL deficiency. Despite surgical debridement every two weeks of the areas the patient continued to have abscess development.

Humoral defects typically predispose patients to recurrent respiratory tract infections. When other systems become involved the clinician must look for other explanations. This case suggests that this humoral and mild cellular defect may have been complicated and made worsen by MBL deficiency. Similar cases of MBL worsening have been reported in association with cystic fibrosis but to our knowledge none have been reported with a primary humoral immunodeficiency.