Maternal influence on IgG subclass antibodies to Bet v 1 during the first 18 months of life as detected with a sensitive ELISA.

BACKGROUND: The initial encounters with allergens are crucial for sensitisation later in life. The IgG1 responses to house dust mite in infancy are later accompanied by an IgG4 response, with high levels seen particularly in atopic children. Little is known of the development of IgG subclass responses to other inhalant allergens. The aims of this study were to develop a sensitive method for the study of postnatal immune responses to the important seasonal inhalant allergen Bet v 1. METHODS: Antibodies to rBet v 1 were analyzed in 96 children at birth, 6 and 18 months using a sensitive enzyme-amplified ELISA. RESULTS: Immunoglobulin G responses to rBet v 1, mainly of the IgG1 subclass, were common in young children, and could at 6 months be demonstrated in several infants who had not yet experienced a postnatal birch pollen season. Atopic dermatitis was associated with high levels of IgG subclass antibodies to birch at 18 months. Maternal atopy was associated with high levels of all IgG subclass antibodies to rBet v 1 in cord blood. In postnatally birch-pollen-exposed infants with atopic mothers, the levels of IgG antibodies at birth correlated with the levels at 6 months. In contrast, high antibody levels to rBet v 1 at birth were associated with low IgG titres to rBet v 1 at 18 months. CONCLUSIONS: IgG1 responses to birch are common during the first 18 months of life. High levels of maternally derived birch-specific IgG antibodies are associated with maternal atopy and may influence the development of the IgG antibody responses to birch in their child.

Antisperm antibodies in infertile women: subclass distribution of immunoglobulin (Ig) A antibodies and removal of IgA sperm-bound antibodies with a specific IgA1 protease.

OBJECTIVE: To determine the immunoglobulin (Ig) A subclass distribution of antibodies in the serum and cervical mucus (CM) of infertile women and to evaluate the effect of an IgA1 protease on the removal of sperm-bound antibodies. METHODS: Twenty infertile women with antisperm antibodies in serum (n = 10) or in CM (n = 10) were recruited for this study. Monoclonal antibodies to human IgA1 and IgA2 were conjugated to immunobeads and the IgA subclass distribution of antisperm antibodies was determined for positive serum and CM samples. The effect of an IgA1 protease (isolated from Neisseria meningitidis strain HF13) on sperm-bound antibodies was evaluated by immunobead binding. RESULTS: In serum, IgA1 subclass antisperm antibodies predominated (89%) when compared to IgA2 (11%). In CM IgA1 accounted for 62% and IgA2 accounted for 38% of the total IgA antisperm antibodies. Enzyme treatment was able to reduce dramatically the amount of serum IgA antibodies bound to sperm from 88% to 10%. Similarly, a significant reduction in CM antisperm antibodies was observed after enzymatic treatment with no loss in sperm motility. CONCLUSION: Cervical mucus antisperm antibodies have a higher proportion of IgA2 subclass suggesting a local production of IgA. Specific IgA1 protease treatment is capable of reducing the amount of immunobead-detectable IgA on sperm. Hamster sperm penetration assays are ongoing to determine if this treatment might improve sperm penetration rates with antibody positive sperm.

Class-specific antibodies to Streptococcus mutans in human serum, saliva and breast milk.

Previous techniques used for the detection and quantitation of antibodies in body fluids may be inappropriate where only small volumes are available, or may not be sensitive enough to detect low levels of specific antibodies. An indirect ELISA technique has successfully been employed to estimate class-specific antibody levels to Streptococcus mutans in serum and secretions in a group of mothers and their neonates, and an attempt has been made to relate such levels to the presence or absence of active caries in the mothers. A high maternal serum IgG antibody level appears to exert a protective effect against dental caries. Antibody levels in maternal saliva and colostrum/breast milk showed no differences between the 2 groups. The presence of active caries in mothers was associated with an elevated IgA antibody level in neonatal saliva. Although ELISA permitted the detection of low levels of antibody in the small volumes of neonatal saliva collected, a further increase in sensitivity and specificity of the assay would be advantageous.

Immunoglobulin classes carrying homocytotropic and passive hemagglutinating antibody activities in the marsupial Setonix brachyurus (the quokka).

On the basis of their physicochemical and antigenic properties, and by analogy with guinea pig immunoglobulins, two antibody classes in the serum of the marsupial Setonix brachyurus have been classified as IgG1 and IgG2 isotypes. The analogy between these marsupial immunoglobulins and those of eutherian (placental) species was extended by an investigation of their biological activities. The electrophoretically slow antibody (IgG2) fixed hemolytic complement, precipitated soluble antigen and predominated early in the response mounted when quokkas were immunized with antigen emulsified in Freund's complete adjuvant (FCA). The more anodic antibody (IgG1) in this marsupial did not fix complement, was inefficient in precipitating antigen and was the predominant antibody synthesized by quokkas immunized with antigen adsorbed to alumina gel. The IgG1 isotype in this marsupial appears to possess both passive hemagglutinating (HA) and homocytotropic antibody (HCA) activities. However, the HCA and IgG1 HA activities did not develop in parallel during the course of the immune response, thus suggesting that only a functional subpopulation of the IgG1 antibodies possess homocytotropic activity.

Availability of locally synthesized and systemic antibodies in the intestine.

The present studies are concerned with the parameters which control the appearance of locally synthesized or serum-derived antibodies in the intestine. The data show that intestinal antibody may be found in rabbits as well as in conventional or germfree mice after active immunization with Vibrio cholerae. However, a large fraction of the intestinal antibody in rabbits and conventional mice originated from the serum as indicated by (i) analysis of correlation between serum and intestinal antibody titers, and (ii) the occurrence of intestinal antibody after parenteral administration of antiserum. In contrast, only locally synthesized 11S immunoglobulin A antibody was detected in the intestine of actively immunized germfree mice. No intestinal antibody was demonstrable in germfree mice after parenteral injection of V. cholerae antiserum. With respect to the appearance of serum antibody in the intestine, the response of conventionalized (ex-germfree) mice was intermediate between that of rabbits or conventional mice and germfree mice. The availability of serum-derived coproantibody in germfree and conventional mice was related to the rates of intestinal degradation of serum antibody. When enzymes were removed by prior washing of intestinal segments, serum antibodies entered the intestine of germfree or conventional mice at similar rates. Rates of entry of serum antibodies into the lumen were comparable at different levels of the small intestine. The presence of a normal enteric flora appeared to protect intestinal antibody from degradation by lowering the concentration or activity of intestinal enzymes. The results are discussed in relation to the question of whether antibacterial immunity to cholera involves local or systemic mechanisms.