The return of the mixed respiratory bacterial vaccine

Background: Orally or sublingually administered lysates of mixed respiratory pathogenic bacteria have been used in Europe, Asia, and other parts of the world, but not the United States, since the mid 1950s, first to prevent recurrent respiratory tract infections, later to prevent wheezing and asthma exacerbations associated with respiratory infections, and, more recently, for the treatment of allergic rhinitis. The apparent success of this treatment contrasts with the negative experience of treating with injections of similar mixed respiratory bacterial vaccines (MRBV or BV) to prevent asthma exacerbations associated with respiratory infections that was once common practice but abandoned ∼50 years ago. Methods: Textbooks and articles on the use of injected BVs to prevent asthma exacerbations associated with respiratory infections were reviewed, including a number of, randomized, double-blind, placebo controlled (RDBPC) studies the results of which were predominantly negative that contributed to the abandonment of this treatment. Also reviewed were more recent articles from Europe and China, which report both clinical and immunologic support for the use of the orally and sublingually administered mixed respiratory bacterial lysates (MRBL or BL). Results: A review of five RDBPC studies of the parenteral use of BVs for prevention of asthma exacerbations conducted by leading international allergists in the 1950s and 1960s showed, in a combined 532 patients, an overall reduction of asthma attacks by 4.9% over placebo. However, in five studies in 1126 patients of oral or sublingual treatment with BLs, the reduction in respiratory infections, wheezing episodes, and asthma exacerbations was 42.6% over placebo. Conclusion: Reported results with oral and sublingual BLs are far superior to the historical performance of injected BVs. Possible reasons for this difference are discussed, but none is clearly responsible for the difference in clinical results.

Comparison of the in-vivo and in-vitro response to ragweed immunotherapy in children and adults with ragweed-induced rhinitis

In order to compare results of allergen immunotherapy in paediatric and adult populations, 22 children with a history of ragweed hay fever were matched with an equal number of adults for skin sensitivity to ragweed and all were given a 1-year course of immunotherapy with a partially purified ragweed extract. Biological responses were measured by nasal challenges with ragweed before therapy was started, after 12 weekly injections and when the maintenance dose had been reached and also by methacholine bronchoprovocation tests before and after 12 months of therapy. Skin-test sensitivity to ragweed and control allergens, and ragweed-specific IgE and IgG antibody responses were measured at the same intervals as the challenges and at the end of the study. The effect of the therapy on clinical symptoms was not evaluated. Before therapy the groups of adults and children were comparable by all indices, except for TAME esterase activity in nasal washes during ragweed nasal challenge which was significantly lower in children. During treatment, mediators released during sequential nasal challenges declined to undetectable levels in most patients and changes in nasal ragweed sensitivity were comparable in both groups. Ragweed IgE increases after 12 weeks of therapy and IgG levels at maintenance therapy tended to be higher in the children, but neither difference was statistically significant. At the end of the study IgE and IgG antibody levels were comparable in both groups. Results of methacholine inhalation tests did not change significantly in either group. The decrease in skin sensitivity to ragweed was similar in both groups. We conclude that ragweed immunotherapy leads to immunological and biological consequences that are comparable in children and adults.

Detection of blocking antibodies after hyposensitization

We have studied two techniques and developed another to detect blocking antibodies in allergic asthmatic children who have been exposed to seven months of hyposensitization to house dust. These techniques were: RAST Neutralization test (RAST-N), RAST Interference test (RAST-I) and RAST Previous Adsorption test (RAST-PA). We have also determined the specific IgE values, by radioallergosorbent test (RAST), before and after the treatment and have not found a significant decrease in these levels. The percentages of positive development of blocking antibodies obtained were: 28% by RAST-N, 80% by RAST-I and 28% by RAST-PA. Thus, RAST Interference test seems to be more sensitive concerning the qualitative determination of blocking antibodies.