A high‐affinity human monoclonal igm antibody reacting with multiple strains of mycoplasma hominis

Abstract

Human monoclonal antibodies were produced against Mycoplasma hominis by in vitro immunization of peripheral blood lymphocytes from a healthy seropositive donor using low amounts of antigen (5 ng/ml). The immune B lymphocytes were subsequently immortalized by Epstein-Barr virus transformation followed by somatic cell fusion. Using this procedure, several specific anti-M. hominis monoclonal antibodies of mu isotype were obtained exhibiting apparent affinity constants as high as 3 x 10(9)M-1. The productivity of a number of different hybridomas was determined to be in the range 7-22 micrograms x (24 hr x 10(6) cells)-1. The specificity of one antibody, 129.1, was further characterized by enzyme-linked immunosorbent assay against several different species of Mycoplasma and by Western blot analysis. The antibody specifically bound to a protein of Mr 100,000 present in 10 of 12 different strains of M. hominis.

The vaa locus of Mycoplasma hominis contains a divergent genetic islet encoding a putative membrane protein

“…Furthermore, the antibody reacted with a 100 kDa protein in all isolates except PG21. This is presumably a protein that has been shown previously to bind Ig-molecules unspecifically, and is not present in PG21 [25]. Apart from the 100 kDa protein the isolates PG21 and 93, having no vmp gene, and isolates 4195 and 7488 having a Vmp-2 and Vmp-3 type, respectively, did not react with the antibody, as expected from the low homology of the C-terminal region (Fig.…”