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Elevated percentage of perforin positive cells in active pulmonary tuberculosis

D Nisha Rajeswari1, P Selvaraj, M S Jawahar

  • 1Tuberculosis Research Centre (ICMR), Chennai, India.

The Indian Journal of Medical Research
|July 29, 2006
PubMed
Abstract

Insights

In active pulmonary tuberculosis, CD8 cells expressing perforin increase, suggesting enhanced cell-killing activity against Mycobacterium tuberculosis. This cytotoxic response is elevated despite normal absolute counts of these cells.

Area of Science:

  • Immunology
  • Cellular Biology
  • Infectious Diseases

Background:

  • Perforin is a key molecule in cytotoxic cell function.
  • The role of perforin-positive cells in tuberculosis (TB) is not fully understood.
  • Pulmonary tuberculosis (PTB) involves complex immune responses.

Purpose of the Study:

  • To quantify circulating CD4(+) and CD8(+) perforin-positive cells in PTB patients.
  • To assess the level of cytotoxic response against Mycobacterium tuberculosis.
  • To investigate the relationship between perforin expression and TB.

Main Methods:

  • Flow cytometry was used to analyze peripheral blood lymphocytes.
  • Specific monoclonal antibodies were employed for intracellular perforin and surface CD4/CD8 staining.
  • Counts of lymphocyte subsets were compared between PTB patients and healthy individuals.

Main Results:

  • PTB patients showed significantly lower total, CD4, and CD8 lymphocyte counts compared to healthy controls.
  • An elevated percentage of total and CD8 perforin-positive cells was observed in PTB patients.
  • Absolute counts of perforin-positive cells (total, CD4, CD8) did not differ significantly between groups.

Conclusions:

  • Active pulmonary TB is associated with an increased percentage of CD8(+) perforin-positive cells.
  • These cells may exhibit heightened cytolytic activity against Mycobacterium tuberculosis.
  • Perforin expression on CD8 cells indicates an active cytotoxic response in pulmonary TB.

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