So lectin has a similar overall function as any PRRs: non-specific recognition of the pathogen.. but only that lectin can help to enhance immune reaction against re-infection of similar pathogens.
As I said, lectin is the most primitive immune system of the organisms that still do not armed by immunocompetent
cells i.e. WBC. PRRs are owned by 'higher' organisms that already have immunocompetent
cells. The principle is similar: to eliminate pathogens and to anticipate them from spreading over the body. The mechanism can be different: agglutination, killing, and/or phagocytosis.
I thought Pathogen recognition and self-non-self differentiation are based on two different mechanisms? That is pathogen (non-self pathogenic) recognition is done by innate immune system (through PRRs).
And self/non-self differentiation is achieved through differentiation of self MHC molecules from non-self MHC and peptide molecules? That is the non-self molecules will trigger an immune response..
Before go any further, you should understand the term "self, nonself", "antigen", "pathogen". Here i try to give you a clue: antigen can be self or nonself protein. Self protein will induce immune tolerance or we will not suffer disease(s). Nonself protein or foreign protein will initiate an immune response(s), the one that makes disease(s) is called "pathogen", whereas the one that triggers allergic reaction(s) is called "allergen".
The antigen recognition via PRRs belongs to innate immunity which the recognition is directly according to pattern-recognition I already mentioned above. The antigen recognition via MHC belongs to adaptive immunity. T-cells cannot recognize antigen directly like macrophage and granulocytes do, so they need a help from some other cells (APCs) to process the antigen into simple peptide and present it with MHC to them. The principle is similar: when PRRs and T-cells find it as self antigen it will lead to immunotolerance, whereas when PRRs and T-cells find it as nonself antigen, it will trigger an immune response. Via PRRs, the response will not specific, via T-cells it will be specific.
I think you know the rest... specific vs nonspecific, don't you?
P.S. Hey you both, what are you talking about?