['The polypeptide transforming growth factor-beta 1 (TGF-beta 1) is a product of activated monocytes, among other inflammatory cells, and it affects immune responsiveness, cellular growth and differentiation. TGF-beta 1 has potent T-cell inhibiting activities. It may play an important role in limiting autoimmune inflammation. We were interested about levels of biologically active and total TGF-beta 1 in serum and CSF in patients suffering from multiple sclerosis.', 'We measured biologically active and total TGF-beta 1 in serum and CSF using ELISA-technique in 64 MS patients with 57 during acute exacerbation of MS and 7 in remission (primary-relapsing: n = 59; primary-progressive: n = 5), 20 healthy subjects, and 21 patients with other non-inflammatory neurological diseases (OND).', 'Biologically active TGF-beta 1 in serum was reduced in MS patients compared to controls, on the other hand total TGF-beta 1 was elevated in CSF compared to patients with OND. Biologically active TGF-beta 1 in CSF correlated positively with the duration of the acute relapse in patients with primary-relapsing MS. The more relapses the patients had the higher was biologically active TGF-beta 1 in CSF. Total TGF-beta 1 in CSF correlated with macrophages in CSF and albumin quotient.'] Is biologically active TGF-beta 1 increased in cerebrospinal fluid while it is reduced in serum in multiple sclerosis patients?