| Causes of Altered Levels |
|---|
| Class | Locations | Functions | Increased | Decreased |
|---|
IgG |
| | Plasma
| Produces antibodies against bacteria, viruses, and toxins
| Infections–all types, acute and chronic
| Lymphocytic leukemia
|
| | Interstitial fluid | Protects neonate | Starvation | Agammaglobulinemia |
| | Placenta | Activates the complement system
Is a major factor in secondary (anamnestic) response | Liver disease
Rheumatic fever
Sarcoidosis
IgG myelomas | Amyloidosis
Toxemia of pregnancy |
| IgA |
| Respiratory tract | Protects mucous membranes from viruses and bacteria
| Autoimmune disease | Lymphocytic leukemia |
| Gastrointestinal tract
Genitourinary tract | Includes antitoxins, antibacterial agglutinins, antinuclear antibodies, and allergic reagins | Chronic infections
Liver disease | Agammaglobulinemia
Malignancies |
| Tears | Activates complement through the alternative pathway | Wiskott-Aldrich syndrome | Hereditary ataxia-telangiectasia |
| Saliva | | IgA myeloma | Hypogammaglobulinemia |
| Milk, colostrum | | | Malabsorption syndromes |
| Exocrine secretions | | | |
| IgM |
| – | Primary responder to antigens
Produces antibody against rheumatoid factors, gram-negative organisms, and the ABO blood group
Activates the complement system | Lymphosarcoma
Brucellosis, actinomycosis
Trypanosomiasis
Relapsing fever
Malaria
Infectious mononucleosis
Rubella virus in newborn
Waldenström's macroglobulinemia | Lymphocytic leukemia
Agammaglobulinemia
Amyloidosis
IgG and IgA myeloma
Dysgammaglobulinemia |
| IgD |
| Serum
Cord blood | Unknown | Chronic infections
IgD myelomas | – |
| IgE |
| Serum
Interstitial fluid | Allergic reactions
Anaphylaxis
Protects against parasitic worm infestations | Atopic skin disorders
Hay fever
Asthma
Anaphylaxis
IgE myeloma | Congenital agammaglobulinemia |