Phospholipase A2 (PLA2), a component of most snake venom toxins, cleaves 3-sn-phosphoglycerides releasing lysophosphatidyl-choline. The indirect quantitative assay method for PLA2 was standardized for specific antivenom titration in a fast and sensitive assay by the similarity with the hemolysis induced by PLA2 and by complement system in sheep erythrocytes. The curves obtained by plotting the degree of hemolysis against the doses of snake venom are concave to the abscissa axis following an equation similar to that previously described for the hemolysis induced by the C system. We observed that venoms of some Bothrops, Crotalus and Micrurus species contained around 1 x 10<img SRC="http:/img/fbpe/jvat/v2n2/image603.gif"> to 10<img SRC="http:/img/fbpe/jvat/v2n2/image604.gif"> Z/mg of venom, while the venom of Naja contained over one million Z/mg. Antibodies against PLA2 were titrated by incubating amounts of venom predetermined to give 1 to 5 Z with various dilutions of the antivenoms, and the remaining active PLA2 was determined in the hemolytic assay. We observed the following: a) the antivenoms contained specific antibodies against the PLA2 present in the corresponding venoms; b) cross-reactivity was not detected among PLA2 epitopes from venoms and nonspecific antivenoms; and c) the assay quantitatively performed determined the specific antibodies directed to epitopes on the molecule of PLA2. The method described in this paper is highly specific, sensitive and reproducible, besides being fast and inexpensive.

Estudou-se sequencialmente, à microscopia eletrônica de transmissão, a interação entre Paracoccidioides brasiliensis (Pb) e células inflamatórias em hamsters inoculados por via intratesticular. Seis horas após inoculações havia predominância de neutrófilos, estando presentes algumas células mononucleares e eosinófilos. Os neutrófilos foram progressivamente substituídos por células mononucleares. Fungos viáveis apresentavam-se fagocitados ou circunscritos por células inflamatórias, geralmente com ampla interface hospedeiro-parasita. Fungos mortos ou degenerados eram acompanhados de interfase estreita. A camada externa da parede do Pb era às vezes quebrada quando em contacto com neutrófilos, em vários pontos, sendo os fragmentos dessa parede descamados e fagocitados. Células fúngicas pequenas com um único núcleo se relacionavam com ampla interfase enquanto as células maiores e multinucleadas apresentavam paredes irregulares, por vezes, contendo lomasoma e/ou estrutura semelhante à mielina. Diferentes padrões de interação do Pb com células do hospedeiro podem ser decorrentes do a fluxo de células inflamatórias funcionalmente diferentes ao local de inoculação ou à idade dos fungos ou ambos os fatores.

Interaction between Paracoccidioides brasiliensis (Pb) and inflammatory cells in hamster testis was studied sequentially by transmission electron microscopy. In early lesions (six hours after inoculation), polymorphonuclear neutrophils (PMNs) were the major and mononuclear cells and eosinophils were the minor constituents of the inflammatory cells. PMNs were later replaced by mononuclear cells. Viable Pb cells were phagocytosed or surrounded by inflammatory cells. Preserved Pb cells usually had broad host-parasite interphases, whereas dying ones had narrow interphases. The outer layer of the fungus wall was sometimes broken by PMN in some focal points, broken pieces being peeled off and phagocytosed. Small Pb cells were uninuclear, and were often related to broad interphase. Large Pb cells were multinucleated with irregularly shaped wall, and sometimes had lomasome and/or myelin like structures. Different interaction patterns of Pb with inflammatory cells may be due to functionally different host cell flow to the inoculation site or due to the age of Pb cells or both.