IN-VITRO INHIBITION OF CRYPTOSPORIDIUM-PARVUM INFECTION BY HUMAN MONOCLONAL-ANTIBODIES

Cryptosporidium parvum infection of the small epithelial intestine cau ses unremitting diarrhea and malabsorption that can lead to chronic an d sometimes fatal illness in patients with AIDS, The illness may be am eliorated by passive oral immunoglobulin therapy, The objective of thi s study was to produce anti-Cryptosporidium human monoclonal antibodie s for evaluation as potential therapy, All human monoclonal cell lines that produced C. parvum antibodies were originally generated from the peripheral blood lymphocytes of a human immunodeficiency virus-serone gative woman, She had recovered from C. parvum infection and had a hig h specific antibody titer, Hybridization of these lymphocytes with a t umor cell line was accomplished by hypo-osmolar electrofusion, Twelve clones were identified by enzyme-linked immunosorbent assay (ELISA) as secreting anti-Cryptosporidium antibodies after the initial hybridiza tion. From the 12 positive clones, two high antibody-secreting clones, 17A and 17B, were maintained in long-term culture, A second hybridiza tion produced two other human monoclonal cell lines, EC5 and BB2, Huma n monoclonal antibody from the first two cell lines bound to C. parvum sporozoites and oocysts by immunofluorescence, The ability of human m onoclonal antibodies to inhibit C. parvum infection in vitro was asses sed by using a human enterocyte cell line, HT29.74, The antibodies of the four different human hybridomas inhibited infection by 35 to 68% ( P < 0.05) compared to a control irrelevant human monoclonal antibody d erived in a similar fashion, Human monoclonal antibodies are candidate molecules for immunotherapy of C. parvum infection.