Various aspects of the allergic reactivity of Amerindians in the Venezuelan sector of the Amazon basin were examined. The frequency of positivity in immediate hypersensitivity skin tests with extracts of common local environmental allergens was found to be extremely low (6.7%). As sera from significantly higher proportions of the study group contained specific IgE antibody against the test allergens, and their histamine-induced skin responses were normal, these results support previous suggestions of an inhibited expression of allergic reactivity in such populations. Indeed, the intense helminthic infections detected, and the extremely high total serum IgE levels measured (geometric mean 13,088 IU/ml) indicate the possible occurrence of mast cell saturation by parasite-induced IgE. However, despite a similar lack of agreement between the in vivo and in vitro tests for allergic reactivity against Ascaris lumbricoides in these subjects (43.5 and 97.9% positive, respectively), their extremely high responsiveness to the helminth allergens presents a marked contrast to that against the other environmental materials. Factors other than helminthiasis (e.g. racial, cultural, nutritional) might, therefore, also modulate the expression of allergic reactivity in such populations.

We previously described an in vitro assay showing that neutrophils (PMNs) from patients with paracoccidioidomycosis (PARA) have a specific digestive deficiency against suspensions of live Paracoccidioides brasiliensis. We now report that this defect is equally detectable against autoclaved, but not Amphotericin B-killed P. brasiliensis. The use of autoclaved suspensions facilitates the use of our in vitro assay. It might allow the development of an in vitro intradermal test for digestion of fungi. Differential digestive ability of phagocytes against live (or autoclaved) and Amphotericin-B killed fungi is of conceptual interest. It may be relevant in understanding therapeutic effect of Amphotericin B.

Zusammenfassung. Neutrophile Granulozyten aus dem peripheren Blut von Paracoccidioidomykose‐Patienten töteten und bauten Paracoccidioides brasiliensis schlechter ab als solche von Gesunden oder von Patienten mit anderen Krankheiten. Die Abtötungsdefizienz war jedoch weniger spezifisch als die Abbaudefizienz, und die Korrelation beider war gering. Daraus wird geschlossen, daß die Abbau‐und die Abtötungsfähigkeit Neutrophiler für P. brasiliensis nicht streng miteinander verschränkte Vorgänge sind und daß der Hauptmangel der Neutrophilenfunktion bei Paracoccidioidomykose‐Patienten die mangelnde Abbaufähiegkeit für P. brasiliensis ist. Summary. Peripheral blood neutrophils (PMN) from patients with paracoccidioidomycosis killed and digested Paracoccidioides brasiliensis much less than did PMN from normal individuals or from patients with other diseases. However, deficiency in killing ability was less specific than digestive deficiency and correlated poorly with it. We conclude that the capacities of PMN to digest and kill P. brasiliensis are not intimately related phenomena, and that in paracoccidioidomycosis the key deficiency of neutrophil function is that of digestion of P. brasiliensis.

Serum from patients with paracoccidioidomycosis (PARA) did not block digestive abilities of neutrophils (PMNs) from healthy individuals against Paracoccidioides brasiliensis. Conversely, serum from healthy donors did not enhance digestive capacities of PMNs from patients with PARA vis á vis the causative organism. We conclude that the specific digestive defect present in PMNs from patients with PARA is not mediated by serum factors.

Samples of alveolar macrophages (AM) obtained by bronchoalveolar lavage from patients with either paracoccidioidomycosis, silicosis, sarcoidosis, or allergic alveolitis were investigated by electron microscopy and immunocytochemistry to compare cellular ultrastructure and expression of MHC-II antigens in the AM cell surface. All samples of AM obtained from patients with these pathologies showed heterogeneous structural features. Although, this morphological diversity is also present in AM of healthy donors, our observations seem to indicate that in the diseases studied this morphofunctional diversity is associated with additional ultrastructural characteristics inherent to each disease. In paracoccidioidomycosis the proportion of vacuolated macrophages is significantly lower than in other diseases; this might indicate that in paracoccidioidomycosis the proportion of activated AM is smaller. We observed significant differences in the expression of MHC-II antigens. Silicosis, sarcoidosis, and allergic alveolitis do not differ significantly in the quantity of immunolabeled AM or in the distribution of the label. The percentage of AM from paracoccidioidomycosis that exhibit the MHC-II molecule is very low with poor immunolabeling. In this disease the low expression of the MHC-II molecule could be related to a decrease of the antigen presenting function by AM.