Early and progressive helper T-cell dysfunction in feline leukemia virus-induced immunodeficiency.
Cats infected with the highly pathogenic feline leukemia virus isolate FeLV-FAIDS develop an immunodeficiency syndrome characterized by progressive loss of CD4+ T cells and eventual pan-lymphocyte depletion. Prior to the decline in circulating CD4+ cells, infected cats are unable to mount primary antibody responses to T-dependent antigens. We investigated whether the altered ability of helper T cells to produce cytokines necessary for B cell growth and differentiation might be a primary event in the pathogenesis of FeLV-FAIDS infection. We found that as early as 9 weeks after infection, lymphocytes from cats with normal CD4+ cell numbers produced significantly lower levels of B-cell stimulatory factors. This deficit became progressively more severe with time. By contrast, resting B cells isolated from infected cats did not differ from controls in the ability to undergo activation and differentiation to antibody-secreting cells. The results suggest that a progressive defect in Th function occurs prior to CD4+ T-cell depletion early in the course of FeLV-FAIDS induced immunodeficiency.
Diehl
L J
LJ
Department of Pathology, Colorado State University, Fort Collins 80523.
Hoover
E A
EA
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D002415:Cats; D016181:Feline Acquired Immunodeficiency Syndrome / Q000209:etiology / Q000276:immunology* / Q000503:physiopathology; D015483:HIV Antibodies / Q000096:biosynthesis; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D005256:Leukemia Virus, Feline / Q000235:genetics; D015183:Restriction Mapping; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D015483:HIV Antibodies; D007376:Interleukin-2; D015850:Interleukin-6