Differential expression of neurofilament triplet proteins in carcinoid tumours: an immunohistochemical study.

Neurofilaments (NFs) are specific intermediate filaments to neural cells. Mammalian NFs are protein triplets composed of three major subunits with respective molecular weights of approximately 70, 150 and 200 kD. Using an immunohistochemical method, 13 carcinoid tumours from different sites were examined for the presence of these three subunits by means of monospecific antisera. All tumours contained cells that were positive for the 70 Kd subunit; nine cases contained cells immunoreactive for the 150 Kd subunit and only three of them for the 200 kD subunit. The results indicate that the 70 kD subunit is a good overall marker of carcinoid tumours. The 150 and 200 kD subunits are more likely to be absent in carcinoids, both typical and atypical.