180 EVIDENCE FOR DIFFERENTIAL PROCESSING OF CHROMOGRANIN A IN NEUROENDOCRINE TUMOURS. Johnston CF, Pogue KM, Curry WJ, Gill DJO, Shaw C, Buchanan KD. Department of Medicine, The Queen's university of Belfast, Institute of Clinical Science, Grosvenor Road, Belfast, BTI2 6BJ, N Ireland. Antisera to chromogranin A (CgA), a ubiquitous neuroendocrine granule constituent, are employed in routine diagnostic pathology. However, CgA has been implicated as the precursor of peptides such as pancreastatin (Pst) and WE-14, and displays different proteolytic processing patterns in different tissues. The present study reports the immunostaining patterns of 76 neuroendocrine tumours with antisera to whole CgA, the C-termina] decapeptide of pancreastatin (CgA 292-301), CgA 315-321 (SKEWEDS) and KELTAE, the C-terminus of WE-14 (CgA 332-337). All tumours displayed similar positivities to CgA, Pst and SKEWEDS. However, only a subpopulation of tumours were immunoreactive for KELTAE, 50% (n=10) of phaeochromocytomas, 30% (n=4) of islet cell tumours and 30% (n=5) of lung carcinoids. No appendiceal carcinoid (n=3) or medullary carcinoma of the thyroid (n=6) displayed any KELTAE immunoreactivity despite being strongly positive for the other markers. Therefore, CgA is differentia]ly processed in different neuroendocrine tumours with WE-14 produced in only 50%. No attempt has been made in the present study to correlate immunostaining patterns with prognosis.
NPY-, F M R F a m i d e - , L P L R F a m i d e - , A N D P Y Y - L I K E P E P T I D E S A R E C O L O C A L I Z E D IN THE B R O C K M A N N B O D I E S OF TWO TELEOSTS. Ann-Cathrine J 6 n s s o n , D e p a r t m e n t of Z o o p h y s i o l o g y , U n i v e r s i t y of G6teborg, Sweden A n u m b e r of r e g u l a t o r y p e p t i d e s h a v e b e e n f o u n d in e n d o c r i n e c e l l s of t h e B r o c k m a n n b o d i e s of t h e t e l e o s t s r a i n b o w t r o u t (Oncorhynchus mykiss) a n d c o d (Gadus morhua) ( J 6 n s s o n , C e l l T i s s u e Res 1991, 2 6 6 : 1 6 3 - 1 7 3 ) . S o m e of t h e s e p e p t i d e s h a d s i m i l a r l o c a t i o n s at the p e r i p h e r y of t h e B r o c k m a n n b o d i e s . T h e p r e s e n t s t u d y w a s a i m e d to e x a m i n e t h e p o s s i b i l i t y of c o - l o c a l i z a t i o n of t h e s e p e p t i d e s . Immunohistochemistry w a s p e r f o r m e d on t i s s u e s e c t i o n s u s i n g d o u b l e s t a i n i n g w i t h a n t i s e r a r a i s e d in r a b b i t s a n d g u i n e a p i g s . T h e s e c o n d a r y a n t i b o d i e s w e r e c o u p l e d to e i t h e r T R I T C o r FITC, a n d t h e s t a i n i n g w a s v i e w e d b y u s i n g t w o s e t s of f i l t e r s on t h e s a m e preparation. M o s t c e l l s i m m u n o r e a c t i v e to N P Y a l s o c o n t a i n e d F M R F a m i d e - a n d LPLRFamide-like immunoreactivity. The staining with LPLRFamide and FMRFamide were often weaker. NPY and PYY-like immunoreactivities w e r e o f t e n f o u n d in t h e s a m e c e l l s . T h e r e w e r e m o r e N P Y - l i k e c e l l s than PYY-like cells. Some cells containing PYY-like immunoreactivity also stained with LPLRFamide- and FMRFamide-antisera. A l a r g e v a r i e t y of a b s o r p t i o n c o n t r o l s indicated that the s t a i n i n g w a s n o t d u e to c r o s s r e a c t i v i t y . F u r t h e r m o r e , p r e i n c u b a t i n g the sections with normal serum did not affect the staining pattern. In c o n c l u s i o n , c e l l s at t h e p e r i p h e r y of t h e B r o c k m a n n b o d i e s in b o t h s p e c i e s c o - l o c a l i z e N P Y - , F M R F a m i d e - , L P L R F a m i d e - a n d P Y Y like immunoreactivity in at l e a s t o n e s u b p o p u l a t i o n of t h e c e l l s .