Background: Patients receiving immunosuppressive therapy with corticosteroi
ds and cytotoxic agents may develop opportunistic infections such as Pneumo
cystis carinii pneumonia (PCP). This indicates a severe T-cell defect, but
so far there a re no established criteria for identifying patients at risk.
Patients and Methods: CD4+ and CD8+ T-lymphocyte counts were determined by
flow cytometry in seven HIV-negative patients who developed PCP as a compli
cation of immunosuppressive treatment.
Results: CD4+ T-lymphocyte counts (T-helper phenotype) were less than 200/m
u l in all seven patients (mean 90.6/mu l). The markedly reduced CD4 counts
measured in these patients are similar to those observed in organ transpla
nt recipients who developed PCP during immunosuppressive therapy for preven
tion of graft rejection and in HIV-positive patients with PCP as an AIDS-de
Conclusion: Measuring CD4+ T-lymphocyte counts may be helpful in determinin
g the risk of PCP not only in HIV-positive patients, but also in patients r
eceiving immunosuppressive therapy. The risk of acqiring PCP seems to incre
ase when CD4+ lymphocyte counts drop below 200/mu l, regardless of the unde