# Temperature-Dependent and Semi-Quantitative Enzyme Profiles of Malacosoma disstria (Lepidoptera: Lasiocampidae) Hemocytic Cell Lines

## TL;DR

This study shows that cell lines from Malacosoma disstria hemocytes can maintain temperature-dependent traits and immune responses, offering a useful model for studying invertebrate immunity.

## Contribution

The study introduces semi-quantitative methods to assess enzyme profiles in hemocytic cell lines, revealing their autonomous immune responses and temperature dependencies.

## Key findings

- M. disstria hemocytic cell lines preserve temperature-dependent traits observed in vivo but show morphological and population differences.
- Semi-quantitative methods detect autonomous innate immune responses in these cell lines, independent of systemic regulation.
- Enzyme secretion profiles change in response to microbial exposure, indicating potential for studying immune signaling.

## Abstract

What are the main findings?
Ex vivo hemocyte populations derived from Malacosoma disstria (Lepidoptera: Lasiocampidae) demonstrated the capacity to preserve select temperature-dependent characteristics observed under in vivo conditions; however, notable variations in cellular morphology and population frequency per hemocyte type were evident when compared with their natural physiological state.Established hemocytic cell lines from M. disstria exhibit the ability of autonomous innate immune responses independent of systemic regulatory influences present in vivo, with such responses being readily detectable using semi-quantitative methodologies.

Ex vivo hemocyte populations derived from Malacosoma disstria (Lepidoptera: Lasiocampidae) demonstrated the capacity to preserve select temperature-dependent characteristics observed under in vivo conditions; however, notable variations in cellular morphology and population frequency per hemocyte type were evident when compared with their natural physiological state.

Established hemocytic cell lines from M. disstria exhibit the ability of autonomous innate immune responses independent of systemic regulatory influences present in vivo, with such responses being readily detectable using semi-quantitative methodologies.

What are the implications of the main findings?
The floating and adherent polystyrene-cultured cell lines derived from M. disstria demonstrate distinctive physiological and immunological properties, establishing a valuable experimental framework for elucidating innate immune mechanisms in invertebrates.Semi-quantitative approaches for hemocytic cell line enzymatic detection can yield valuable insights concerning the temporal dynamics governing enzyme release, thereby establishing a foundation for elucidating the kinetic parameters that drive cellular processes.

The floating and adherent polystyrene-cultured cell lines derived from M. disstria demonstrate distinctive physiological and immunological properties, establishing a valuable experimental framework for elucidating innate immune mechanisms in invertebrates.

Semi-quantitative approaches for hemocytic cell line enzymatic detection can yield valuable insights concerning the temporal dynamics governing enzyme release, thereby establishing a foundation for elucidating the kinetic parameters that drive cellular processes.

Insect hemocytic cell lines offer substantial advantages over primary, in vivo hemocyte cultures, fundamentally transforming experimental approaches in cellular immunology and related fields. Selected Malacosoma disstria cell lines were characterized for optimal growth temperatures, morphogenesis, blebbing, extracellular enzyme profiles, and their interactions with material (polystyrene) and microbial (Bacillus subtilis) surfaces. The adhesive hemocyte lines UA-Md221 and Md108 showed optimal growth at 28 °C, whereas UA-Md203 and Md66 grew best at 21 °C, with Md66 tolerating 21–28 °C. Md108 demonstrated a broader temperature tolerance than other adherent cultures. Both Md108 and UA-Md221 adhered to polystyrene within 24 h post-subculturing, although protease-induced morphological changes in modified Grace’s medium continued through 48 h and 72 h, respectively. Culture quality was monitored by assessing the release of multiple enzymes, including alkaline and acid phosphatases, esterases and lipases, aminopeptidases, proteases, glycosidases, and hydrolases from the cell lines at 50% confluency in modified Grace’s medium. Fetal bovine serum showed elevated esterase lipase (C8) and phosphoamidase activities when diluted in Grace’s medium and phosphate buffered saline (PBS). Exposure to dead B. subtilis suspended in PBS induced quantitative and qualitative alterations in the enzyme secretion profiles of Md66 and Md108 cultures. We conclude that semi-quantitative assessments of hemocytic cell lines can provide valuable insights for the time window of each enzyme release, revealing immune and metabolic signaling patterns.