Bacterial immunomodulator Olimunostim inhibits degranulation of mastocytes in vitro.

: 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 in patients suffering from infection complicated allergic diseases (asthma bronchiale, atopic eczema, etc.), (1) the concentration of histamine (Hi) and Hi-like compounds in OS, and (2) the possible role of OS in 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. acnes) by original modification of high-performance liquid chromatography. The data provide the first evidence for a dose-dependent inhibitory effect of OS on the degranulation of rat PMC. Moreover, we found that 1 mg of OS itself contained 0.376 microgram of Hi and 0.142 microgram of 1-methylHi. Histamine was detected in P. acnes (0.672 microgram/mg), K. pneumoniae (0.136 microgram/mg), and S. aureus (0.175 microgram/mg), while methylHi was detected only in the case of K. pneumoniae (0.454 microgram/mg). The results of our in vitro study do not support the hypothesis of inducing type I allergic reaction by OS or facilitating OS in crossing the enteral barrier.