Suppression of parasitemia in rodent filariasis (Litomosoides carinii) by immunization with BCG and microfilaria. I. Intracutaneous inoculation of BCG

After intracutaneous inoculation of BCG and challenge by subcutaneous injection of infective larvae of Litomosoides carinii, the parasitaemia of the filarial infection in cotton rats remains significantly lower when BCG and larvae are applied in the region of the same popliteal and ileal lymph nodes. However, when the infective larvae are directed to other regional lymph nodes (Ln cubitales and axillares), the depression of microfilaraemia is missed. The worm load (recovery rate) and the expulsion of microfilariae by the adult worms are not influenced by the BCG inoculation. Obviously BCG stimulates the lymphatic tissue unspecifically, and the infective larvae produce the first antigen contact, which is boostered by the microfilariae at the onset of patency. When the intracutaneous BCG inoculation is combined with specific antigen stimulation by simultaneous injection of blood microfilariae in the region of the same lymph nodes, the microfilaraemia of the challenge infection disappears completely or remains extremely low.     

Ein neuer Phytophthorabiotyp auch in Bayern?

Ohne ZusammenfassungBayrischen Landes-Saatzucht-Anstalt Weihenstephan.     

Studies on acquired resistance of the cotton rat against microfilariae of Litomosoides carinii. 2. Injection of microfilariae during prepatency

Cotton rats infected by infective third-stage larvae of Litomosoides carinii were treated at increasing time intervals by a threefold injection of living homologous microfilariae (mf) during the prepatent period. Starting with the first treatment 3, 4 or 5 weeks p.i. seven animals remained completely and two almost mf-negative (1 or 2 mf/mm3 each only once) until 16 weeks p.i. Starting 6, 7 or 8 weeks p.i. six animals developed a normal level of parasitaemia between 42 and 436 mf/mm3, two animals developed a continuous level of 1-2 mf/mm3. The number of fertile adult worms shedding great numbers of microfilariae in the pleural cavity was equal in all animals. However, in mf-negative animals the lung capillary blood showed, in the geometric mean, only 0.6% of the mf-concentration seen in mf-positive animals. The hypothesis is proposed that microfilariae accumulating primarily in the lung capillaries absorb all aggressive components specifically reacting with microfilarial antigens, i.e. neutralize the immune response against them to enable the development of the parasitaemia in the peripheral blood.