[Production of interferon and alpha 2-macroglobulin involvement in immune response during human viral hepatitis A (author's transl)].

In viral hepatitis A, we could distinguish between monophasic and polyphasic forms. Monophasic and polyphasic hepatitis A induce the production of plasma interferon. Interferon level, elevated as early as the first days following the appearance of clinical signs, decreases and reaches a minimum value on the seventh day. A new rise of interferon is characterized by a maximum level on the twelfth day and a minimum level on the thirtieth. Beyond the first month we could still detect the presence of interferon. In the two forms of hepatitis, a complement system is activated both by classical and alternate pathways. IgM levels increase early, IgA levels remain unchanged. On the other hand, IgG levels, only slightly elevated in monophasic hepatitis A, are highly increased in polyphasic hepatitis A beyond the first month. Alpha 2-macroglobulin reaches levels above normal during convalescence in monophasic hepatitis A; on the contrary, in polyphasic hepatitis A, alpha 2-macroglobulin levles are above normal as early as the thirty first days of illness and remain above normal for several months. Elevated levels in alpha 2-macroglobulin may inhibit cellular immunity which is accountable for immunological injury of virus infected hepatocytes. We wonder whether this earlier increase in alpha 2-macroglobulin is responsible for the lasting character of viral infection observed in polyphasic hepatitis A.