A. Serum immunoglobulins – Explanation
This patient has had repeated infections with encapsulated bacteria which should raise the suspicion
of immunoglobulin deficiency. HIV would be suggested by infections associated with impaired
cellular immunity.
Immunoglobulins
The table below summarizes the characteristics of the 5 types of immunoglobulin found in the body:
| IgG | 75% | Monomer | Enhance phagocytosis of bacteria and viruses, pass to fetal circulation |
| IgA | 15% | Monomer/Dimer | Found in secretions, provide localized protection on mucous membranes |
| IgM | 10% | Pentamer | First to be secreted, anti-A, B blood antibodies |
| IgD | 1% | Monomer | Involved in activation of B cells |
| IgE | 0.1% | Monomer | Involved in allergic reactions |
