A bacterial immunomodulator Olimunostim (OS) is one of the first Czech
biologic response modifiers, which have been introduced into clinical
practice, OS activates the mechanisms of non-specific immunity and is
used for the most part in chronic infections, Since OS is indicated i
n patients suffering from infection complicated allergic diseases (ast
hma bronchiale, atopic eczema, etc.), (1) the concentration of histami
ne (Hi) and Hi-like compounds in OS, and (2) the possible role of OS i
n the process of histamine release from rat peritoneal mastocytes (PMC
) were studied. The cells were preincubated with soluble fractions of
OS. PMC degranulation was stimulated by the compound 48/80. The amount
of Hi and Hi-like substances in the supernatant and in the pellet of
PMC was determined by the fluorimetric method, Compounds of Hi nature
were also evaluated in OS (lysate of S. aureus, K. pneumoniae, P. acne
s) by original modification of high-performance liquid chromatography,
The data provide the first evidence for a dose-dependent inhibitory e
ffect of OS on the degranulation of rat PMC. Moreover, we found that 1
mg of OS itself contained 0.376 mu g of Hi and 0.142 mu g of 1-methyl
Hi, Histamine was detected in P. acnes (0.672 mu g/mg), K. pneumoniae
(0.136 mu g/mg), and S. aureus (0.175 mu g/mg), while methylHi was det
ected only in the case of K. pneumoniae (0.454 mu g/mg). The results o
f our in vitro study do not support the hypothesis of inducing type I
allergic reaction by OS or facilitating OS in crossing the enteral bar
rier.