Germline IgM predicts T cell immunity to Pneumocystis

Area of Science:

• Immunology
• Mycology
• Pediatrics

Background:

• Pneumocystis pneumonia is a common fungal infection in young children.
• Infants with primary immunodeficiency are particularly susceptible to Pneumocystis.
• Maternal IgG levels are low and IgM is dominant in infants aged 3-6 months.

Purpose of the Study:

• To investigate the role of fungal-specific IgM in early Pneumocystis infection.
• To identify Pneumocystis antigens recognized by IgM.
• To determine if IgM specificities predict T cell antigens.

Main Methods:

• Detection of fungal-specific IgM in human and mouse sera.
• Immunoprecipitation to identify shared antigens.
• T cell response assessment to identified antigens.
• Class II MHC binding prediction and peptide design.
• Adoptive transfer of T cells.

Main Results:

• Fungal-specific IgM was detected in human cord blood and mouse sera.
• Shared Pneumocystis antigens were identified.
• Designed peptides elicited robust peptide-specific lung T cell responses.
• Vaccine-elicited CD4+ T cells demonstrated effector activity.

Conclusions:

• Germline-encoded IgM B cell receptors are critical for antigen presentation in early Pneumocystis infection.
• Identified antigens contain protective Pneumocystis epitopes.
• IgM plays a key role in T cell priming against Pneumocystis.