Immunostimulation. Clinical and experimental perspectives

General non-specific morbidity is reduced after vaccination within the third month of life--the Greifswald study

OBJECTIVES

The incidence of many serious infectious diseases fundamentally decline as a success of consequent vaccination regimens. However, it is a matter of discussion if vaccination might cause unspecific negative side effects on the immune system. To answer this, we performed a clinical study on children with the question as to whether there is an enhanced frequency of infection diseases after vaccination or not.

METHODS

The study population (n=496) was randomized to a group of vaccinated children (first vaccination on the 60th day of life, n=201) and a group of unvaccinated children (first vaccination on the 90th day of life, n=295). Frequencies of unspecific, morbidity-related signs were recorded by the mothers with a diary card. These data were taken for further statistical analysis to determine if the factor "vaccination" does have a significant effect on the variable "morbidity".

RESULTS

Various infectious disease-associated symptoms (vomiting, coughing, signs of rhinitis, restlessness, rash and pain) were significantly less often seen in vaccinated than in non-vaccinated children.

CONCLUSIONS

Our study revealed that children who received vaccination against diphtheria, pertussis, tetanus, HiB and poliomyelitis simultaneously within the third month of life do not exhibit enhanced frequencies of infectious disease-associated symptoms. In contrary, the frequencies of infection-associated symptoms were found to be significantly reduced. This might be caused by a vaccination-associated unspecific enhancement of immunological activity (e.g. mediated by interleukin 2) or by other presently still unknown factors.

Prevention of bronchial hyperreactivity in children

Hyperresponsiveness of the bronchi is defined as an excessive reaction of bronchial mucosa to irritants that do no harm to a healthy mucosa. Measures to prevent bronchial hyperreactivity in children with asthma and other diseases remain rather ineffective at present. Though progress has been made in some areas.

Therapeutic ratio of mono or combination bacterial lipopolysaccharide therapy in methylnitrosourea-induced rat mammary carcinoma

Four experiments investigating the antitumor activity of bacterial lipopolysaccharide (LPS) against the autochthonous methylnitrosourea-induced mammary carcinoma are summarized. Administration of LPS alone i.v. caused distinct regression of small tumors following its first injection. This therapeutic effect, however, was short-lived and could not be maintained by administering a second dose. The observed antineoplastic activity of LPS was dose-related, whereas no dose-response relationship was observed with respect to its toxicity. A series of experiments in which LPS was combined with other compounds to possibly exploit its activity while reducing the toxicity were performed. Neither the combination with cytotoxic drugs such as 4'-(9-acridinylamino)-methansulfone-m-aniside or cyclophosphamide nor that with 1-octadecyl-2-methoxy-rac-glycero-3-phosphocholine or hexadecylphosphocholine showed sufficient anticancer activity at acceptable toxicity. In all experiments promising efficacy was observed at high dosages but also high toxicity. When the dosages were reduced, diminished antineoplastic activity was found together with overproportionally high mortality. It might therefore be concluded that the active dose range of LPS cannot be reached clinically because of its inherent toxicity.

Combinations of two synthetic adjuvants: synergistic effects of a surfactant and a polyanion on the humoral immune response

Synergistic effects of two synthetic adjuvants, dimethyldioctadecylammonium bromide (DDA) and dextran sulfate (DXS) on the humoral response to sheep red blood cells (SRBC) were investigated. Mice received intraperitoneal (ip) injections of adjuvant and antigen simultaneously. The number of plaque-forming cells (PFC) in the spleen were determined 5 days later and circulating anti-SRBC antibodies were measured till 16 weeks after immunization. Although combinations of DDA and DXS were very effective in enhancing the PFC response to both moderate (2 X 10(7] and low (2 X 10(6] doses of SRBC, synergy between the adjuvants was only observed at the low dose of SRBC. Optimal augmentation of the primary response to the low antigen dose was evoked by the combination of the highest dose tested of either adjuvant (1 mumol DDA and 1 nmol DXS) resulting in a 560-fold increase of the number of PFC in the spleen as compared to controls. Even combinations of relatively small amounts of both adjuvants were very effective in augmenting the response to SRBC. Mice receiving half the amounts of both adjuvants with 2 X 10(6) SRBC displayed increased numbers of PFC in the spleen at Day 5 as well as increased titers of total anti-SRBC antibodies at Week 1 and Week 2 and 2-mercaptoethanol-resistant antibodies from Week 4 till Week 16 as compared to the calculated sum of responses in mice which received either DDA (0.05 mumol per mouse) or DXS (0.05 nmol per mouse). The mechanism behind the synergy between these adjuvants is discussed and the possibility of discerning adjuvants on their modes of action is suggested.