Search

The association of IgA deficiency with SLE is clearly established but occurs in only a small percentage of patients. Several hypotheses address the relationship between the two disease processes but the common link remains undetermined. It is important to investigate the diagnosis of IgA deficiency in patients presenting with SLE in order to provide the most appropriate treatment. This patient not only represents a rare presentation of SLE but highlights the uncommon occurrence with IgA deficiency and brings forth valuable teaching points of both diseases.

Total IgA, IgM, IgG, and IgG subclasses were measured in 136 consecutive adults with recurrent respiratory infections. Sinus and chest radiographs were also obtained. IgG antibodies to H. influenzae and tetanus toxoid were determined in 27 immunodeficient subjects. Fifty-eight of the 136 were deficient in some immunoglobulin isotype, three in IgA, three in IgM, and 52 in total IgG or one or more IgG subclasses. The most common IgG deficiencies were single IgG subclass deficiencies, particularly IgG3 or IgG4, and a mild decrease in total IgG (between 450 and 650 mg/dL). In 21/27 subjects with IgG deficiency, the response to booster immunization was blunted, even when IgG1 and IgG2 were normal. Thirty-eight patients were smokers, 37 being40 years of age at the onset of respiratory infections. Twenty patients were nonsmokers, 19 being40 years of age at the onset. In conclusion, adults with recurrent respiratory infections frequently have some variant of IgG deficiency, often associated with a functional impairment of specific antibody response. Smoking may represent a risk factor for IgG deficiency in adults.

Secretory IgA is known to play a major role in the exclusion of foreign antigens from the systemic compartments. We have previously shown that IgA-deficient subjects can have large amounts of circulating immune complexes containing bovine antigens of dietary origin, presumably due to the defective secretory barrier. In these studies, we investigated whether the peak amount of immune complexes found after specific antigen challenge could be related to the level of serum or salivary IgA. Our data show that the peak of immune complex is not related to either serum or salivary IgA but that it is closely correlated to the titer of antibody to milk proteins. In addition, it appears that some individuals with only modest IgA deficits can have substantial mucosal permeability defects on milk challenge.

A 6-year-old girl with congenital agammaglobulinemia exhibited severe delayed onset cutaneous reactions to mosquito bites with scar formation. The bites were not associated with immediate reactions accompanied by itching. The patient had non-detectable IgE levels (less than 0.2 IU/mL) in addition to absence of three other major classes of immunoglobulins, but showed normal T cell functions. Immunologic and histopathologic examination of the skin lesions revealed that this unusual reaction may be caused by a delayed type hypersensitivity response.

All individuals are exposed to large amounts of potentially immunogenic food proteins. Most people respond by producing IgG, IgA, or IgM antibodies. The presence of such antibodies in serum is a normal, but not necessarily physiologic phenomenon. In certain groups of individuals, such as young infants, persons with a selective IgA deficiency and patients with inflammatory gastrointestinal disorders, especially high levels of such antibodies are commonly found despite complete tolerance to intake of the food in question. Obviously the finding of IgG, IgA or IgM antibodies to food proteins in serum is of limited clinical relevance. The presence in serum of IgE antibodies to food antigens is not uncommon in some patients with atopic dermatitis, although the clinical relevance of the antibodies for the dermatitis is not always clear. Young, atopic children have low levels of such antibodies as a normal, transient phenomenon. High concentrations of IgE antibodies not only to classical food antigens such as egg, fish, cow's milk, nuts, shellfish, peanuts and cereals but also to less typical allergens such as celery, some spices and other vegetables often indicate a pronounced food allergy that can give rise to a serious reaction upon contact. In contrast to the case with non-IgE antibodies, the presence of IgE antibodies in serum is a non-physiologic state of clinical relevance.

In this study the authors investigated the relationship between secretory IgA levels and the appearance of a compensatory mechanism, through IgM action in allergic children.

The pathways leading to the development of the allergic state and subsequently to the characteristic inflammatory response are complex in nature and result from an interplay between immunologic and biochemical events. Along these pathways a number of intrinsic factors, i.e., handling of antigens at mucosal level, transient immunodeficiency states, especially in the secretory IgA system, impairment in the IgE regulatory mechanism, modulation of cyclic nucleotides leading to mediator release and a "feedback" inhibition control provided by histamine and eosinophil derived products greatly dictate the outcome of events associated with allergic inflammation.

Selective IgA deficiency is the most common form of immunodeficiency. Certain select populations, including allergic individuals, patients with autoimmune and gastrointestinal tract disease and patients with recurrent upper respiratory tract illnesses, have an increased incidence of this disorder. These patients have the unique ability to form various antibodies and auto-antibodies including anti-IgA antibodies. Failure of terminal differentiation of the B lymphocyte is the primary defect in IgA deficiency. Treatment should be directed toward the underlying disease associated with this immune disorder. These patients should be advised of the consequences of improperly administered blood or blood products.