the polymerase chain reaction ( pcr ) described by saiki et al ., science 230 , 1350 - 1354 ( 1985 ) was employed hereinafter for the cloning and expression of the variable domain of murine immunoglobulins ( ig ). 1 . identification of the conserved regions at the 5 ′ and 3 ′ end of the murine heavy ig chain ( vh ) and the light ig chain ( vk ). the mutually aligned sequences of the variable regions were taken from the data file of kabat et al . sequences of proteins of immunological interest , us dept . of health and human services , us government printing office ( 1987 ). the nucleotide sequences start there at the amino terminus of the mature protein and do not include the signal sequences . computer screening ( dbutil , r . staden ( 1986 ) nucleic acids res . 14 , 217 - 231 ) was used to find suitable primers for cdna synthesis and amplimers for use in the pcr : oligonucleotide i : bst eii vh1forward 5 ′ tga gga gac ggt gac c gt ggt ccc ttg gcc cca 3 ′ oligonucleotide ii : ck1 5 ′ tgc agc atc agcc 3 ′ oligonucleotide iii : 5 ′ ag gtc cag ctg cag gag tct gg 3 ′ g a a c a psti vh1 backward oligonucleotide iv : 5 ′ gac att cag ctg acc cag tct cca 3 ′ pvuii vk1 backward oligonucleotide v : vk1forward 5 ′ gtt aga tct cca gct tgg tcc c 3 ′ bgl ii rna was prepared from about 3 × 10 8 cells of the particular hybridomas which secrete mab a , b , c or d , and poly a + mrna was enriched from the latter using oligo dt sepharose . the poly a + mrna was used for the cdna synthesis . the first strands of cdna were synthesized using oligonucleotide primers which hybridize in the j region of the v h nucleotide sequences ( oligonucleotide i ) and at the 5 ′ end of the kappa c gene nucleotide sequences ( oligonucleotide ii ). the rna is then decomposed by naoh treatment . the second strands of cdna were synthesized using oligonucleotide primers which hybridize at the 5 ′ ends of the v h ( oligonucleotide iii ) and of the v kappa ( oligonucleotide iv ) nucleotide sequences . the dna generated as described in 2 . was amplified using oligonucleotides i , iii , iv and v ( oligonucleotide v hybridizes in the j region of the v kappa nucleotide sequences ) and the taq dna polymerase from thermophilus aquatius . a typical mixture contained in 50 ll total volume 5 ll of ds dna ( prepared in 2 . ), 25 pmol of amplimers , and was 250 lm in each of datp , dttp , dctp and dgtp , 67 mm tris - hcl ph 8 . 8 , 17 mm ( nh 4 ) 2 so 4 , 10 mm mgcl 2 , 200 lg / ml gelatin and 2 units of taq polymerase . a layer of liquid paraffin was placed on the mixture and then 25 cycles each of 1 min at 95 ° c . ( for denaturation ), 1 min at 30 ° c . ( hybridization ) and 2 min at 72 ° c . ( dna synthesis ) were carried out using a techne phc - 1 programmable heating block . the oligonucleotides used for the cdna cloning and amplification contain restriction cleavage sites . the cdna cloning and the amplification resulted in these restriction cleavage sites being introduced at the 5 ′ end and at the 3 ′ end of the v h and v kappa nucleotide sequences ( pst i and bsteii in v h and pvuii and bglii in v kappa ). these restriction cleavage sites were then used to clone v h and v k cdna fragments in m13 vectors ( lys 19 , lys 17 ) ( verhoyen et al . science 239 , ( 1988 ), 1534 - 1536 ). finally , the nucleotide sequences of the particular v h and v kappa cdna fragments were determined using the method of sanger ( pnas , usa , 74 , 5463 - 5467 , ( 1977 )) from the lys 19 and lys 17 vectors ( see tab . 7 , 8 , 9 , 10 ). examples 4 and 5 shall explain the use of the mab c described using mab c : mab c was fixed to the wells of microtitration plates ( nunc ) by adsorption . into these wells 20 μl sample plus 100 μl buffer - solution ( osnd , behringwerke a g ) each was pipetted and 2 respective 3 hours incubated . after threefold washing with diluted enzygnost r washing solution ( osen , behringwerke a g ) 100 μl conjugate - solution was filled into each well . used here were conjugates of peroxidase with lectin ( e . g . wheat germ agglutinin wga ) or with other antibodies recognizing different epitopes of the tumor - associated antigens defined by mab c . the following two or three hours incubation step at 37 ° c . was terminated by 3 wash cycles . for the third incubation step at room temperature 100 μl each of a buffer / substrate - chromogene solution ( ouvg / ousf behringwerke a g ) was filled into the wells and the enzyme reaction was terminated after 30 min . with 100 μlof stopping solution enzygnost r ( osfa , behringwerke a g ). absorbance of the samples was measured at 450 mm . the absorbance values determined as shown above correspond to the concentration of the antigen ( s ) in the samples . the concentration of the antigen defined by the specific binding of mab c , in serum or plasma of tumor patients is significantly elevated as compared to said concentration of healthy control persons or patients with benign disease . this is especially true for patients with carcinoma of the pancreas ( fig1 ), significantly elevated concentrations were also determined in serum or plasma of patients with carcinoma of the stomach , colon or rectum . equally good results were obtained irrespective of the conjugate system ( antibody - peroxidase or wga - peroxidase ). with the use of mab c as specific binding - component a sensitive test for tumor markers of especially gastrointestinal tumor disease can be made . 5 μg each of mab c or mab c 50 as control ( pharmacia ; holmgren et al . ( 1984 ) british med . j . 288 , 1479 ) were pipeted in 50 μl phosphate - buffered - saline ( pbs ) into a ca 19 - 9 test ( ca 19 - 9 eia “ roche ”). the highest standard ( 100 u / ml ) was added before start of the incubation . the tests were performed according to the instructions of the test - kit above and the absorbances of the respective samples were determined . as shown in fig2 , the additional dilution of the standard - antigen after addition of the pbs - solution reduces the signal of the highest standard even without addition of mab . no further reduction of the signal results by the presence of mab c in the assay . in contrast hereto the signal formation is totally inhibited by mab c 50 , which as is known , binds among others specifically to the epitope “ sialosyl le αn recognized also by mab 19 - 9 : from the above one may conclude that mab c recognizes a different epitope as mab 19 - 9 .
the invention relates to murine monoclonal antibodies , a , b , c and d , which are directed against tumor - associated antigens . the nearly complete nucleotide sequences of the v genes of these mabs are described , so that the relevant variable domains can be put together to give chimeric mabs , or “ humanized ” mabs are obtained by inserting the hypervariable regions into a human mab framework . antibody constructs of this type can be employed in human therapy and in vivo diagnosis without the disadvantages observed with murine mabs .