Responses of T and B lymphocytes to a Paracoccidioides brasiliensis cell wall extract in healthy sensitized and nonsensitized subjects.
Antigen-specific cellular immunity in paracoccidioidomycosis (PCM) has been poorly studied due to lack of standard in vitro lymphocyte proliferation assays. To standardize such an assay, we studied T and B cell responses to a Paracoccidioides brasiliensis cell wall extract (PbAg) in healthy subjects sensitized to either P. brasiliensis [Pb(+)Hc(-)] or to Histoplasma capsulatum [Hc(+)Pb(-)], and in nonsensitized persons. All subjects showed, as expected, a vigorous proliferative response to a control fungal antigen obtained from Candida albicans. Lymphocytes from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) donors, reacted to PbAg by proliferating in a dose-dependent manner with a maximum reaction after 6-9 days, suggesting a secondary specific immune response. Most activated cells were CD+CD4+ lymphocytes. However, Hc(+)Pb(-) donors' cells reacted with PbAg. Cross-reactivity with H. capsulatum was not unexpected, since both fungi, but not C. albicans, share cell wall immunogenic compounds. An enzyme-linked immunosorbent assay to detect human immunoglobulins (Ig) demonstrated that B cells from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) ones, reacted with PbAg by secreting high levels of IgG and IgM in 12-day culture supernatants. This secretion was possibly mediated by PbAg-activated CD4+ cells. We believe that analysis of T and B lymphocyte responses to PbAg will be useful in the investigation of the infection-associated immune impairment seen in some PCM patients.
Benard
G
G
Immunogenetics and Experimental Transplantation Laboratory, Faculdade de Medicina, Universidade de Sao Paulo, Brazil.
Durandy
A
A
Assis
C M
CM
Hong
M A
MA
Orii
N M
NM
Sato
M N
MN
Mendes-Gianini
M J
MJ
Lacaz
C S
CS
Duarte
A J
AJ
D000946:Antigens, Fungal / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002176:Candida albicans / Q000276:immunology; D002473:Cell Wall / Q000276:immunology; D003429:Cross Reactions; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006658:Histoplasma / Q000276:immunology; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007111:Immunity, Cellular; D007114:Immunization; D007136:Immunoglobulins / Q000276:immunology; D007231:Infant, Newborn; D008297:Male; D010228:Paracoccidioides / Q000276:immunology* / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000276:immunology*
D000946:Antigens, Fungal; D007136:Immunoglobulins