Pentraxin 3 is the first detected and so far the most important protein from the recently recognized group called the long pentraxins. The structure and function of PTX3 resembles in many aspects that of the short or classical pentraxins, i.e. C-reactive protein and the serum amyloid P component. There are, however, several important differences between the two groups of pentraxins that will be mentioned in more detail in the article. All of the above mentioned pentraxins take an acitve part in the first-line defense of the host against invading pathogenic microorganisms and in the clearance of the host’s own apoptotic cells. The latter mechanism impedes the onset of destructive autoimmune reactions. A biologically relevant antipode of PTX3 is represented by TNFα. Physiologic course of the defense reactions depends on a closely co-ordinated activity of both peptides. In case of an unchecked or missing activity of either peptide, a disturbance in their mutual balance results in increased susceptibility of the host to conditionally pathogenic fungi or in increased damage to host’s own tissues inflicted by the defense reactions. This review article deals with the physiopathologic importace of pentraxin 3 as has been gained on the basis of the most up-to-date information.

        Key words: pentraxin 3, C-reactive protein, cytokines, the complement system, apoptosis, dendritic cells, T lymphocytes, Aspergillus fumigatus.