Immunoregulatory activities of lactoferrin in the delayed type hypersensitivity in mice are mediated by a receptor with affinity to mannose.

The mannose receptor (MR) mediates clearance of pathogenic microorganisms and potentially harmful glycoproteins by recognition of the carbohydrate structures. This manuscript describes the significance of the MR in mediation of the lactoferrin (LF) effects in delayed type hypersensitivity (DTH) in mice. Here we demonstrate that the inhibitory effect of LF on the effector phase of DTH to sheep red blood cells (SRBC) was abolished by intraperitoneal (i.p.) pretreatment of mice with 50 mg of methyl-alpha-D-mannopyranoside (MMan). Also, we report that the inhibition of the effector DTH response to ovalbumin (OVA) was reversed by MMan but not by D-galactose (Gal). MMan was found to reduce the adjuvant activity of LF given together with OVA, however, did not interfere with the upstimulatory effect of the complete Freund's adjuvant. Comparative studies between bovine and human lactoferrins (BLF and HLF), revealed that the adjuvant effect of BLF was stronger than that of HLF, nevertheless, both effects were inhibited by MMan. Thus, we postulate, that MR is a primary receptor for lactoferrin in mediation of its some immunotropic activities.