Immunosuppression in Kenyan visceral leishmaniasis

Area of Science:

• Immunology
• Infectious Diseases
• Tropical Medicine

Background:

• Visceral leishmaniasis is an endemic parasitic disease in Kenya.
• Cell-mediated immunity plays a crucial role in controlling leishmaniasis.
• Understanding immune responses is vital for managing the disease.

Purpose of the Study:

• To evaluate cell-mediated immune responses in Kenyan patients with active visceral leishmaniasis.
• To assess both in vivo and in vitro immune reactions to various antigens and mitogens.
• To investigate the nature and extent of immunosuppression in visceral leishmaniasis.

Main Methods:

• Skin testing with leishmanin, tuberculin, streptococcal, and candida antigens in patients and controls.
• In vitro lymphocyte blastogenic transformation assays using phytohaemagglutinin (PHA), concanavalin A (Con A), purified protein derivative (PPD), streptokinase-streptodornase (SKSD), and leishmanial antigen (LA).
• Comparison of immune responses between patients with active visceral leishmaniasis and age/sex-matched controls.

Main Results:

• The majority of patients exhibited complete anergy (unresponsiveness) to all tested antigens both in vivo and in vitro.
• Suppression of lymphocyte responses to non-specific mitogens (PHA, Con A) was less pronounced than to specific antigens.
• Recovery of non-specific immune responses was observed to precede the development of specific immunity.
• A subset of patients (23%) showed persistent immune unresponsiveness to leishmanial antigens one year post-treatment.

Conclusions:

• Visceral leishmaniasis in Kenya is associated with profound specific and non-specific immunosuppression.
• Immune recovery is a gradual process, with non-specific responses often returning before specific immunity.
• Persistent immune unresponsiveness post-cure highlights potential challenges in complete disease resolution and relapse prevention.