|dc.description.abstract||Allergic conditions among workers processing seafood are most often related to inhalation of
the seafood antigens or via direct unprotected handling of the seafood and its products. This
can cause sensitised individuals to suffer from asthma, rhino-conjunctivitis, urticaria and
protein contact dermatitis, which are IgE mediated. Food intolerance may also occur which is
a non-IgE mediated reaction, however the exact mechanism is yet to be determined. There is
therefore a need to develop reliable tests to identify sensitised workers processing seafood.
The objective of this study was to prepare specific seafood extracts from raw and cooked
lobster; raw and cooked saltwater bony fish species (mackerel, red eye, maasbanker, pilchard
and anchovy) and fishmeal dust obtained from a fish-processing factory. These extracts were
tested by SDS-Polyacrylamide Gel Electrophoresis to characterise the seafood proteins, and
the allergenicity was confirmed by the Western blot technique. Polyclonal IgG antibodies
were also successfully generated in rabbits, using the specific seafood extracts isolated from
the various species.
The second objective was to optimise and standardize an Enzyme Allergosorbent Test
(EAST) method to quantify specific IgE antibodies in the sera of factory workers. This EAST
was optimised and validated to detect allergen-specific IgE to each of the different fish
species and also one crustacean species (rock lobster). Sera from a group of workers were
selected and analysed for specific IgE antibodies by the optimised EAST (S) (South African
laboratory), and commercial RAST techniques. Analysis was performed for the three most
important extracts, pilchard (canned), anchovy, and lobster. The same samples were analysed
by EAST (R) in the reference laboratory (Dr Gerald Reese; Paul-Ehrlich-Institute, Germany).
The different techniques, and the EAST (R) and the EAST (S) results were compared by
using a statistical software package.
An EAST method was successfully developed, however, compared to the results obtained by
the reference laboratory the sensitivity and specificity was below 80%. The main reason for
the low agreement between the two laboratories was the fact that the South African laboratory
used a modified EAST method, and different data calculation methods, for categorising
positive results. The South African laboratory did not use a kit-based assay and a serum
dilution of 1:4 and not 1:2 were used when compared to the reference laboratory. When the
EAST results were compared to the RAST results, poor agreement was found due to the fact
that canned pilchard was used in the EAST while raw pilchard in the commercial RAST
assay. For pilchard, anchovy and lobster EAST, different species were utilized compared to
the RAST, and this can also explain the poor level of agreement.
Future directions would be to further standardise the EAST method and to introduce reference
sera and a standard curve to determine positive results, thereby ensuring more reproducible
results between laboratories.||