Cutaneous response to PHA-M and hematological changes in corticosteroid treated cows

Area of Science:

• Immunology
• Veterinary Medicine
• Pharmacology

Background:

• Phytohemagglutinin (PHA) is a plant lectin used to assess cell-mediated immunity.
• Corticosteroids are potent anti-inflammatory agents with known effects on immune responses.
• Understanding the impact of corticosteroids on PHA-induced skin reactions in cattle is crucial for interpreting immune function tests.

Purpose of the Study:

• To investigate the effect of corticosteroid administration on the cutaneous reaction to intradermal phytohemagglutinin in normal cattle.
• To analyze the associated hematological changes following phytohemagglutinin injection in both control and corticosteroid-treated cattle.

Main Methods:

• Normal cattle were treated with corticosteroids.
• Intradermal injections of phytohemagglutinin (PHA) were administered.
• Skin thickness changes and hematological parameters were measured and compared between treated and untreated groups.

Main Results:

• Corticosteroid-treated cattle exhibited approximately 50% reduction in skin thickness increase compared to controls following PHA injection.
• The cellular infiltrate in the skin reaction shifted from early neutrophilic predominance to later lymphoid cell dominance at 72 hours in normal animals.
• Hematological analysis revealed physiological leukocytosis in normal animals, while corticosteroid-treated animals showed neutrophilia, lymphopenia, eosinopenia, and monocytosis.

Conclusions:

• An intact inflammatory mechanism is essential for a normal cutaneous response to phytohemagglutinin.
• Corticosteroids significantly suppress the inflammatory skin reaction to PHA in cattle.
• Observed hematological changes in corticosteroid-treated cattle are consistent with those seen in other species.