Protection against Pneumocystis carinii pneumonia by antibodies generated from either T helper 1 or T helper 2 responses

Beth A. Garvy, James A. Wiley, Francis Gigliotti, Allen G. Harmsen

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


To determine whether different antibody isotypes associated with T helper 1 (Th1) or Th2 responses are protective against Pneumocystis carinii, mice with disrupted interleukin 4 genes (IL-4(-/-) mice) or gamma interferon genes (IFN-γ(-/-) mice) along with wild-type C57BL/6 mice were immunized intratracheally against P. carinii, depleted of T cells in vivo by use of monoclonal antibodies, and rechallenged intratracheally with 107 viable P. carinii organisms. Nearly all immunized mice resolved their lung P. carinii infections (limit of detection, log10 4.06) within 21 days of challenge even though they were depleted oft cells. Unimmunized mice depleted oft cells had significant lung infections (>log10 5.5) at day 21 post-P. carinii challenge. IFN-γ(-/-) and wild-type mice developed P. carinii-specific immunoglobulin primarily of the immunoglobulin G1 (IgG1) subclass with relatively little P. carinii-specific IgG2a, IgG2b, or IgG3 in their sera, characteristic of a Th2-type response. In contrast, IL-4(-/-) mice had primarily an IgG2b P. carinii-specific antibody response in their sera with very little IgG1. Although IgG2b was the predominant isotype in IL-4(-/-) mice, optical density values of IgG2a and IgG3 were significantly higher in these mice (two and three times, respectively) than in IFN-γ(-/-) mice, characteristic of a Th1-type response. Together, these data indicate that resolution of P. carinii infection can be mediated by specific antibody responses and that the antibody response can be either a predominantly Th1 or Th2 type. Furthermore, although wild-type mice mounted a Th2-like antibody response, IL-4(-/-) mice could resolve P. carinii pneumonia, indicating that resistance to P. carinii can occur in the absence of IL-4.

Original languageEnglish
Pages (from-to)5052-5056
Number of pages5
JournalInfection and Immunity
Issue number12
StatePublished - 1997

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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