Cell-mediated immunity during natural measles infection

Area of Science:

• Immunology
• Virology
• Cellular Biology

Background:

• Measles infection is known to cause prolonged depression of cell-mediated immunity.
• The precise mechanisms by which measles influences lymphocyte function remain incompletely understood.

Purpose of the Study:

• To investigate the properties and function of lymphocytes during and after measles infection.
• To elucidate the impact of measles on T-cell and B-cell behavior and immune responses.

Main Methods:

• Quantification of lymphocyte populations (T cells, B cells) via immunofluorescence.
• Assessment of lymphocyte proliferation using phytohemagglutinin (PHA) and Candida antigen stimulation.
• Measurement of lymphocyte viability after incubation with autologous serum and complement.
• Evaluation of leukocyte migration index using heat-killed Candida cells.

Main Results:

• A decrease in circulating thymus-derived lymphocytes (T cells) during acute measles, with 37% of PHA-stimulated T cells showing measles virus staining.
• Impaired lymphocyte proliferation in autologous serum, with significantly reduced responses to Candida antigen compared to recovery phase.
• Reduced leukocyte migration index to Candida antigen during acute measles, improving post-recovery.
• Evidence of measles virus within B cells, though their numbers remained stable.

Conclusions:

• Measles infection leads to T-cell depletion and impaired lymphocyte proliferation, partly due to serum inhibitors and potential defects in antigen processing.
• These factors collectively contribute to the depression of cell-mediated immunity observed in measles patients.
• The findings highlight the complex interplay of viral effects and host immune responses in measles pathogenesis.