is consistent with the molecular weight of the tcr u03b1 u03b2 complex and of cd3 chains u03b5 u03b4 respectively under reducing conditions the 85 kd band dissociates into two bands of 40 and 50 kd which is consistent with molecular weight of the tcr u03b1 and u03b2 chains respectively the immunoblot of one of the anti h 243 specific mab is shown in fig1 together with okt3 as a positive control and an irrelevant mab as a negative control table iii shows cross reactivity of the mab with six v u03b29 positive t cell clones two v u03b18 positive t cell clones and eight other t cell clones with different v u03b1 and v u03b2 39 s antibody tcr 74 should be regarded as v u03b29 specific as it agglutinates all the v u03b29 positive t cells and not the others the other tcr antibodies only react with h 243 so it is very likely that these antibodies are directed against the antigen binding part of h 243 as reaction with v u03b18 v u03b29 constant region of tcr u03b1 u03b2 cd3 and other common t cell surface molecules is excluded fig2 shows that antibodies from the hybridoma clones tcr 64 tcr 66 tcr 69 tcr 70 tcr 73 and tcr 76 mab are able to stain the tcr on a non reduced western blot 85 kd band the non specific heavy bands at the top of the figure are descended from the immunoprecipitating antibodies sam and okt3 no staining with the anticlonotype mab was obtained in a western blot ran under reducing conditions results not shown suggesting that the mab recognize a conformation epitope formed by the intact tcr u03b1 u03b2 complex to investigate whether the mab are able to induce proliferation of h 243 t.