CONCLUSIONES FINALES

(a) To investigate and determine the levels of total and allergen-specific IgG4 and IgE in non-atopic and atopic patients during pregnancy and to compare these levels with those in the same patients after pregnancy. (b) To correlate the laboratory findings with that of clinical manifestations of

allergic symptoms.

CHAPTER FOUR

4.1 Study Location

This project was undertaken at the Langold Health Centre, Worksop in Nottinghamshire. The Health Centre cares for a population of 7000 patients. Almost the entire population is of European stock. Most of the patients are in the mining industry and some are involved in agriculture and professions, e.g. teachers, office workers, etc. The practice area is surrounded by agricultural lands and woodlands.

4.2 Preliminary Environmental Survey

It is well established that clinical manifestations of hayfever relate to

environmental factors, particularly the pollen count. A preliminary survey was

carried out to investigate the environmental factors pollen count, rainfall and temperature and also to identify the principal plant species known to generate allergenic pollen found in the geographical location of the clinical study area. The local pollen counts, obtained from the National Pollen Count Centre at Rotherham - 10 miles north of Langold, were analyzed for three consecutive years during the pollen seasons in 1984, 1985 and 1986 (Appendix I). Fig. 2, Appendix I, shows monthly pollen count, rainfall and temperature from May to August 1985.

The principal allergic pollen-generating species in the area are shown in Appendix I. It can be seen that the parishes from which the practice population are drawn contain over 1000 ha of grassland and it was thus likely that grass pollen would be a common allergen in this population.

4.3 Preliminary Patient Selection

A preliminary survey was undertaken to determine the most common allergen affecting the population so that this could be examined in the

subsequent study of pregnancy. This preliminary study also enabled a clear understanding of the clinical manifestations of hayfever and of any significant local variations to be obtained. It also provided a basis for a comparison of the clinical symptoms in the pregnant and non-pregnant population. Practice hayfever sufferers were invited to join the preliminary study. In response to a notification that allergy screening facilities were available in the practice, a total of 75 known hayfever patients attended for allergy screening.

4.4 Diagnostic Procedures

Clinical History

In allergy, as in any other branch of medicine, history taking is all important. In order to achieve an accurate history comparable between individual cases and to arrive at a clear presumptive diagnosis, an allergy case

history from (Form 1, Appendix II) was designed.

Clinical Examination

This included a general examination with special attention to chest symptoms such as asthma, nasal polyp, deviated nasal septum and eczema lesions.

Skin Testing

For the purpose of identification of local allergen distribution among the practice population and also for the identification of a model allergen for further laboratory investigations, the modified skin prick test was used.

A single drop of allergen extract was placed on the skin, on the inside of the forearm. Allergen testing solutions were prepared from aqueous allergen extracts containing 50 per cent glycerin and 0.4 per cent phenol in 3 ml dropper bottles. These solutions are standardised by the manufacturers by iso-electric

focusing to ensure constant potency and reproducible results. Allergy concentrations are quoted as protein nitrogen units (PNU) per unit volume. The allergen was dissolved in normal saline and a stilette introduced through the drop of allergen into the skin at an acute angle and followed by a single vertical lift. Test solutions were separated from each other and results were compared with negative and positive controls. The responses, which appeared as wheals of different sizes, were evaluated after 10 to 20 minutes. The results recorded

on form III (Appendix II). Skin test kits were produced and provided by E.

Merck Pharmaceuticals, Alton, U.K.

Interpretation of Results of Skin Test

The wheals were graded as either +, ++, +++, ++++, or +++++, according to diameter (Table 6). In order to avoid confusion and operator error, these tests were carried out by a single operator.

4.5 Summary of Results of Preliminary Screening

The study was conducted in a rural setting in England covering a population of approximately 7000 people. Pollen counts in the summer months of three consecutive years showed that June 1984 and June 1986 had similar daily average pollen count of 103 where as June 1985 had an average pollen count of 62 for the same period.

A total of seventy five patients with allergic symptoms attended for preliminary screening (Table 7). Forty two of these were male and thirty three were female. Among the male patients, seven suffered from perennial symptoms, twenty eight with seasonal symptoms and seven with perennial symptoms with seasonal exacerbations. Among the female patients, ten had perennial symptoms, twenty one seasonal and two reported seasonal exacerbation of symptoms.

Extracts of thirty two different allergens were tested, depending on the history of individual allergic symptoms. The top three positive reactions to plant pollens were against grass (54) barley (35) and wheat (19). Appendix III Table 8 shows the distribution of skin test reactions.

The age of onset of symptoms in the attendant group was reported to be from the very young (under 2 years of age) up to the age of 48 years (Appendix ID Tables 9 and 10).

Appendix III gives full details of the patients screened and the results of