Screening for IgE mediated allergy among people working in the Marseilles harbour.

Screening for IgE mediated allergy by RASTs to professional (castor bean, green coffee, peanut, soy protein, wheat, rice), and non professional (pollens, mites, cat, Alternaria tenuis) air borne antigens among 36 people working in the Marseilles harbour has showed rather unexpected findings: only one case of IgE positivity to Dermatophagoides pteronyssinus (class I) and one case of IgE positivity to castor bean seed (Ricinus communis) (class IV). IgG4 specific antibodies against castor bean and green coffee were also measured by an ELISA technique, with eleven cases of positivity to castor bean and only one case to green coffee being recorded. Several explanations can be put forward for the low incidence of IgE responses to the commonest airborne antigens and to the professional antigens (castor bean being the only offender), and for the rather high incidence of specific IgG4 antibodies to castor bean. Most likely, the low incidence of latent atopy is the result of a natural selection among the workers who gave up their job if experiencing of discomfort. As far as the elevated IgG4 antibody levels to castor bean are concerned, these are probably natural blocking antibodies.