ABSTRACTS XVI ALASBIMN CONGRESS  NUCLEAR MEDICINE 1999.

7. BONE ORTHOPEDICS, BONE- JOINTS DIS

7.15 INTERVERTEBRAL DISC INJURY CAN BE DETECTED USING RADIOLABELED MONOCLONAL ANTIBODY KERATAN SULPHATE

K.J.A. Kairemo, A. Lappalainen, E. Kääpä, 0. Laitinen, T. Hyytinen, S. Strömberg, T. Erselcan, S-L. Karonen, M. Grönblad

Depts. of Clin. Chem and Phys. Medicine & Rehab., Helsinki Univ.

Central Hospital, Univ. of Veterinary Medicine, Helsinki, Finland.

Kalevi.Kairemo@huch.fi

We have developed an intervertebral disc injury model for analyzing sulphated glycosaminoglycans in vivo. Keratan sulphate (KS) is most abundant of these in the inner nucleus pulposus (NP) and less abundant in the outer fibrosus (AF).

A radioiodinated (I-125) monoclonal antibody (MAb) raised against KS was injected into rats (n=6) and following biodistribution data was obtained at 72 hr: blood 0.18, heart 0.38, liver 0.48, spleen 0.45, kidney 0.65, bone 0. 16 and muscle 0. 17 X 10^-2 % injected, activity/gram tissue. In the disc injury model two tail discs in each animal with both acute (2 wk) and subacute (7 wk) injuries were studied for in vivo antibody uptake. There was a significant difference in the antibody uptake between injured discs (0.39 X 10^-2 % ID/g, n=12) and adjacent healthy discs (0.34 X 10^-2 % ID/g, n=12) both after acute and subacute injury.

In vivo gamma imaging using I-125-MAb demonstrated increased take in other animals having lumbar disc injuries (2, 7 and 17 days Id). Cartilaginous tissue, such as trachea, was studied separately, and t demonstrated extremely high antibody uptake. Rat trachea was also visualized on gamma images.

Our data suggests that antibodies against NP structures, such as proteoglycans, can be used for in vivo detection of intervertebral disc injury. This is inspite of minimal circulation in the AF itself and NP.

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