In the present study, IgM antibody response was found positive in 2 (18.2%) HIV seropositive Cryptosporidium positive (Gp I) and 2 (20%) HIV seronegative Cryptosporidium positive (Gp III) including 1 (100%) post-transplant (Gp IIIa) patient while in the Cryptosporidium negative groups (Gp II, IV and V), 2 (8%) patients with other parasitic infections showed positive response. The gene discussed is CD40LG; the disease is parasitic infectious disease.