Several V genes participate in the early phenyloxazolone response in various combinations

Seventeen monoclonal anti‐2‐phenyloxazolone antibodies from the early (day 7) primary response were partially sequenced with an mRNA method. Ten antibodies expressed the VH−Ox1 gene. The remaining seven express at least four but probably six different germ‐line VH genes belonging to Dildrop's groups 1, 5, 6 and 7 (Immunol. Today 1984. 5: 85). Two of them have been met before in other antibodies, one (group 6) in J606 and the other (group 7) in antibodies to the influenza virus hemagglutinin. Eleven kappa chains were partially sequenced and five of them (all VH−Ox1 antibodies) express the Vx−Ox1 gene. One expresses another germ‐line gene of the Vx−Ox1 family, one the Vx89.4 gene, three the Vx45.1 gene and one a new Vx gene. The Vx45.1 gene was found to form anti‐phox antibodies with two new VH genes. The frequency of somatic mutations in day 7 antibodies was estimated by comparing germ‐line sequences and antibody sequences. It is low (one mutation per 2500 nucleotides sequenced), twenty times lower than in antibodies obtained a week later. Two anti‐idiotype antisera (495 and 260) are useful in the typing of monoclonal antibodies. 260 bound only to antibodies coded by both VH−Ox1 and Vx−Ox1 genes. 495 bound strongly to antibodies coded by the VH−Ox1 gene and weakly to antibodies coded by the (related) VH101 gene regardless of the light chain partner.