SUMMARYExpression of CAM PATH-1H. a hutnanized MoAb directed against an abundant surface antigen on human lymphocytes, has been studied using transfected tnycloma cells. As the site of chromosome integration of DNA transfected into a cell is random we investigated the feasibility and frequency of hitting a'jackpot'site for expression after co-transfection with CAMPATH-IH heavy and light chain constructs in genomic context. A cell line generating 40 ^ig/ml of CAMPATH-IH in spent culture supernatant was achieved. The full nucleotide sequence of the CAMPATH-IH heavy and light chain cDNA clones is also shown, in addition a comparison of the efleclor mechanisms, antibody dependent cellular cytotoxicity and complement dependent cytotoxicity. of myeloma cell and Chinese hamster ovary (CHO) cell-derived CAMPATH-IH is reported.

Metacercariae of Fasciola hepatica were excysted in a simple system based on the stimuli determined by Dixon (1966). Reproducibly high levels of excystment (70-80%) were obtained within 3h. Equal volumes of human serum and medium RPMI 1640 with 2% washed human red blood cells supported better growth in vitro than human serum diluted with ELac or NCTC 135. Reduced rates of growth were observed with serum concentrations lower than 50%. During culture over a period of 14 weeks some organisms in every culture grew to a length of 3 mm at a linear rate approximately one quarter of the growth rate in vivo (mouse). A few parasites suddenly began to develop more rapidly after six weeks in culture and reached 6-7 mm in length, comparable to the size of sexually mature Fasciola grown in mice. These cultured worms showed extensive development of the uterus, vitellaria, and testes with spermatozoa. The ovary remained rudimentary and egg formation did not occur.

Surface components of Schistosoma mansoni have been identified by lactoperoxidasecatalyzed iodination. Cercariae have a simple labeling pattern in comparison to schistosomula. Transformation of cercariae to schistosomula results in the loss of a low molecular weight material which may be the glycocalyx, and the appearance of many more labeled proteins. Mechanical conversion of cercariae to schistosomula requires subsequent incubation at 37 degrees C for more than 1 h to give the full surface-labeling pattern of schistosomula. The majority of proteins found on schistosomula appear to be present throughout the remaining part of the developmental cycle, although adult male worms had only low levels of these antigens, and female worms had virtually no detectable surface antigens. The low level of expression of schistosome antigen could be caused by adsorbed host antigen, although no evidence for adsorbed host protein was found, or by a reduced level of antigens present on the worm surface. The low level of schistosome antigen could have a role in the resistance of adult worms to the host's immune response.

SUMMARYTwo hybridomas secreting monoclonal IgM antibody to Schistosoma mansoni have been isolated following fusion of spleen cells from Balb/c mice immunized with living S. mansoni and NS1 myeloma cells. One monoclonal IgM antibody (WP66.4) mediated about the same level of passive protection against a challenge infection as immune serum from mice with a chronic S. mansoni infection. The other monoclonal antibody (WP66.2) did not give a significant level of passive protection. This result indicates that the effective monoclonal antibody recognizes an antigen which may be a valuable candidate for experimental vaccination. In vitro one monoclonal antibody (WP66.4) caused a much higher level of complement-dependent cytotoxicity than the other (WP66.2), suggesting a possible mechanism for the effect observed in vivo. With indirect immunofluorescence both monoclonal antibodies reacted with surface determinants on living S. mansoni schistosomula, adult worms and miracidia but these determinants were not detected on cercariae or lung schistosomula. Neither monoclonal antibody cross-reacted with S. haematobium schistosomula or Fasciola hepatica metacercariae, indicating a possible use for these reagents in differential diagnosis of S. mansoni infections.

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