Host-parasite relationship and immune responses elicited depend of the nature of the substances produced by the parasite. H. lineatum proteins have been extensively studied and characterized. These proteins are implicated in immunomodulation process in both the inflammatory system and the specific immune system. These data suggested that after primary infection L1 larvae were able to escape to the host inflammatory system. This lack of reactivity can be explained by some anti-inflammatory functions of hypodermins.
Inflammatory cells are also the target of the anti-inflammatory activity of hypodermins.
All these anti-inflammatory activities of parasite proteases may have relevance to in vivo reactions and may explain the lack of reactivity observed around the larvae in naive animals. Specific immune responses appear to be also modulated by hypodermins. This lack of antigenicity may be associated with the structure of this protein. Carbohydrates are less antigenic than peptides and this may be the reason for the impaired host immune reaction. This delayed immune response at primary infestation suggested that parasites may induce immunosuppression of the cellular response.