Anaphylaxis inhibitory factor: clinical evaluation in pediatric patients

A factor similar to that reported in mouse, capable of inhibiting the passive cutaneous anaphylactic reaction (PCA), has been demonstrated in human sera. The present study reports the laboratory and clinical evaluation of this factor in pediatric patients. A low percentage of the allergic patients (7.7%) showed the inhibitory factor and a positive skin test, while 70% of the nonallergic patients showed the inhibitory factor and a negative skin test. The absence of this factor showed a significant relationship with the presence of allergy (p < 0.001) and with a positive skin test (p < 0.01), although no relationship was observed with total plasma IgE levels (p > 0.05). Thus, it is concluded that PCA inhibitory factor modifies the expression of IgE without affecting its synthesis. The absence of this factor allows the expression of IgE in allergic patients with positive skin tests. The clinical implication demonstrated indicates that this may be a useful tool in the study of allergic patients.